wip

The actual unoptimized bytecode contains one additional instruction but this is definitely a bit faster in benchmarks

integrations/cli/index.test.ts

@@ -23,7 +23,7 @@ describe.each([
     'Standalone CLI',
     path.resolve(__dirname, `../../packages/@tailwindcss-standalone/dist/${STANDALONE_BINARY}`),
   ],
-])('%s', (_, command) => {
+])('%s', (kind, command) => {
   test(
     'production build',
     {
@@ -628,6 +628,194 @@ describe.each([
       ])
     },
   )
+
+  test(
+    'production build + inline source maps',
+    {
+      fs: {
+        'package.json': json`
+          {
+            "dependencies": {
+              "tailwindcss": "workspace:^",
+              "@tailwindcss/cli": "workspace:^"
+            }
+          }
+        `,
+        'ssrc/index.html': html`
+          <div class="flex"></div>
+        `,
+        'src/index.css': css`
+          @import 'tailwindcss/utilities';
+          /*  */
+        `,
+      },
+    },
+    async ({ exec, expect, fs, parseSourceMap }) => {
+      await exec(`${command} --input src/index.css --output dist/out.css --map`)
+
+      await fs.expectFileToContain('dist/out.css', [candidate`flex`])
+
+      // Make sure we can find a source map
+      let map = parseSourceMap(await fs.read('dist/out.css'))
+
+      expect(map.at(1, 0)).toMatchObject({
+        source: null,
+        original: '(none)',
+        generated: '/*! tailwi...',
+      })
+
+      expect(map.at(2, 0)).toMatchObject({
+        source:
+          kind === 'CLI'
+            ? expect.stringContaining('node_modules/tailwindcss/utilities.css')
+            : expect.stringMatching(/\/utilities-\w+\.css$/),
+        original: '@tailwind...',
+        generated: '.flex {...',
+      })
+
+      expect(map.at(3, 2)).toMatchObject({
+        source:
+          kind === 'CLI'
+            ? expect.stringContaining('node_modules/tailwindcss/utilities.css')
+            : expect.stringMatching(/\/utilities-\w+\.css$/),
+        original: '@tailwind...',
+        generated: 'display: f...',
+      })
+
+      expect(map.at(4, 0)).toMatchObject({
+        source: null,
+        original: '(none)',
+        generated: '}...',
+      })
+    },
+  )
+
+  test(
+    'production build + separate source maps',
+    {
+      fs: {
+        'package.json': json`
+          {
+            "dependencies": {
+              "tailwindcss": "workspace:^",
+              "@tailwindcss/cli": "workspace:^"
+            }
+          }
+        `,
+        'ssrc/index.html': html`
+          <div class="flex"></div>
+        `,
+        'src/index.css': css`
+          @import 'tailwindcss/utilities';
+          /*  */
+        `,
+      },
+    },
+    async ({ exec, expect, fs, parseSourceMap }) => {
+      await exec(`${command} --input src/index.css --output dist/out.css --map dist/out.css.map`)
+
+      await fs.expectFileToContain('dist/out.css', [candidate`flex`])
+
+      // Make sure we can find a source map
+      let map = parseSourceMap({
+        map: await fs.read('dist/out.css.map'),
+        content: await fs.read('dist/out.css'),
+      })
+
+      expect(map.at(1, 0)).toMatchObject({
+        source: null,
+        original: '(none)',
+        generated: '/*! tailwi...',
+      })
+
+      expect(map.at(2, 0)).toMatchObject({
+        source:
+          kind === 'CLI'
+            ? expect.stringContaining('node_modules/tailwindcss/utilities.css')
+            : expect.stringMatching(/\/utilities-\w+\.css$/),
+        original: '@tailwind...',
+        generated: '.flex {...',
+      })
+
+      expect(map.at(3, 2)).toMatchObject({
+        source:
+          kind === 'CLI'
+            ? expect.stringContaining('node_modules/tailwindcss/utilities.css')
+            : expect.stringMatching(/\/utilities-\w+\.css$/),
+        original: '@tailwind...',
+        generated: 'display: f...',
+      })
+
+      expect(map.at(4, 0)).toMatchObject({
+        source: null,
+        original: '(none)',
+        generated: '}...',
+      })
+    },
+  )
+
+  // Skipped because Lightning CSS has a bug with source maps containing
+  // license comments and it breaks stuff.
+  test.skip(
+    'production build + minify + source maps',
+    {
+      fs: {
+        'package.json': json`
+          {
+            "dependencies": {
+              "tailwindcss": "workspace:^",
+              "@tailwindcss/cli": "workspace:^"
+            }
+          }
+        `,
+        'ssrc/index.html': html`
+          <div class="flex"></div>
+        `,
+        'src/index.css': css`
+          @import 'tailwindcss/utilities';
+          /*  */
+        `,
+      },
+    },
+    async ({ exec, expect, fs, parseSourceMap }) => {
+      await exec(`${command} --input src/index.css --output dist/out.css --minify --map`)
+
+      await fs.expectFileToContain('dist/out.css', [candidate`flex`])
+
+      // Make sure we can find a source map
+      let map = parseSourceMap(await fs.read('dist/out.css'))
+
+      expect(map.at(1, 0)).toMatchObject({
+        source: null,
+        original: '(none)',
+        generated: '/*! tailwi...',
+      })
+
+      expect(map.at(2, 0)).toMatchObject({
+        source:
+          kind === 'CLI'
+            ? expect.stringContaining('node_modules/tailwindcss/utilities.css')
+            : expect.stringMatching(/\/utilities-\w+\.css$/),
+        original: '@tailwind...',
+        generated: '.flex {...',
+      })
+
+      expect(map.at(3, 2)).toMatchObject({
+        source:
+          kind === 'CLI'
+            ? expect.stringContaining('node_modules/tailwindcss/utilities.css')
+            : expect.stringMatching(/\/utilities-\w+\.css$/),
+        original: '@tailwind...',
+        generated: 'display: f...',
+      })
+
+      expect(map.at(4, 0)).toMatchObject({
+        source: null,
+        original: '(none)',
+        generated: '}...',
+      })
+    },
+  )
 })
 
 test(

integrations/package.json

@@ -4,6 +4,7 @@
   "private": true,
   "devDependencies": {
     "dedent": "1.5.3",
-    "fast-glob": "^3.3.3"
+    "fast-glob": "^3.3.3",
+    "source-map-js": "^1.2.1"
   }
 }

integrations/postcss/index.test.ts

@@ -712,3 +712,68 @@ test(
     await retryAssertion(async () => expect(await fs.read('dist/out.css')).toEqual(''))
   },
 )
+
+test(
+  'dev mode + source maps',
+  {
+    fs: {
+      'package.json': json`
+        {
+          "dependencies": {
+            "postcss": "^8",
+            "postcss-cli": "^11",
+            "tailwindcss": "workspace:^",
+            "@tailwindcss/postcss": "workspace:^"
+          }
+        }
+      `,
+      'postcss.config.js': js`
+        module.exports = {
+          map: { inline: true },
+          plugins: {
+            '@tailwindcss/postcss': {},
+          },
+        }
+      `,
+      'src/index.html': html`
+        <div class="flex"></div>
+      `,
+      'src/index.css': css`
+        @import 'tailwindcss/utilities';
+        @source not inline("inline");
+        /*  */
+      `,
+    },
+  },
+  async ({ fs, exec, expect, parseSourceMap }) => {
+    await exec('pnpm postcss src/index.css --output dist/out.css')
+
+    await fs.expectFileToContain('dist/out.css', [candidate`flex`])
+
+    let map = parseSourceMap(await fs.read('dist/out.css'))
+
+    expect(map.at(1, 0)).toMatchObject({
+      source: '<no source>',
+      original: '(none)',
+      generated: '/*! tailwi...',
+    })
+
+    expect(map.at(2, 0)).toMatchObject({
+      source: expect.stringContaining('node_modules/tailwindcss/utilities.css'),
+      original: '@tailwind...',
+      generated: '.flex {...',
+    })
+
+    expect(map.at(3, 2)).toMatchObject({
+      source: expect.stringContaining('node_modules/tailwindcss/utilities.css'),
+      original: '@tailwind...',
+      generated: 'display: f...',
+    })
+
+    expect(map.at(4, 0)).toMatchObject({
+      source: expect.stringContaining('node_modules/tailwindcss/utilities.css'),
+      original: ';...',
+      generated: '}...',
+    })
+  },
+)

integrations/utils.ts

@@ -5,7 +5,9 @@ import fs from 'node:fs/promises'
 import { platform, tmpdir } from 'node:os'
 import path from 'node:path'
 import { stripVTControlCharacters } from 'node:util'
+import { RawSourceMap, SourceMapConsumer } from 'source-map-js'
 import { test as defaultTest, type ExpectStatic } from 'vitest'
+import { createLineTable } from '../packages/tailwindcss/src/source-maps/line-table'
 import { escape } from '../packages/tailwindcss/src/utils/escape'
 
 const REPO_ROOT = path.join(__dirname, '..')
@@ -42,6 +44,7 @@ interface TestContext {
   expect: ExpectStatic
   exec(command: string, options?: ChildProcessOptions, execOptions?: ExecOptions): Promise<string>
   spawn(command: string, options?: ChildProcessOptions): Promise<SpawnedProcess>
+  parseSourceMap(opts: string | SourceMapOptions): SourceMap
   fs: {
     write(filePath: string, content: string, encoding?: BufferEncoding): Promise<void>
     create(filePaths: string[]): Promise<void>
@@ -104,6 +107,7 @@ export function test(
       let context = {
         root,
         expect: options.expect,
+        parseSourceMap,
         async exec(
           command: string,
           childProcessOptions: ChildProcessOptions = {},
@@ -591,7 +595,9 @@ export async function fetchStyles(base: string, path = '/'): Promise<string> {
   }
 
   return stylesheets.reduce((acc, css) => {
-    return acc + '\n' + css
+    if (acc.length > 0) acc += '\n'
+    acc += css
+    return acc
   }, '')
 }
 
@@ -603,3 +609,82 @@ async function gracefullyRemove(dir: string) {
     })
   }
 }
+
+const SOURCE_MAP_COMMENT = /^\/\*# sourceMappingURL=data:application\/json;base64,(.*) \*\/$/
+
+export interface SourceMap {
+  at(
+    line: number,
+    column: number,
+  ): {
+    source: string | null
+    original: string
+    generated: string
+  }
+}
+
+interface SourceMapOptions {
+  /**
+   * A raw source map
+   *
+   * This may be a string or an object. Strings will be decoded.
+   */
+  map: string | object
+
+  /**
+   * The content of the generated file the source map is for
+   */
+  content: string
+
+  /**
+   * The encoding of the source map
+   *
+   * Can be used to decode a base64 map (e.g. an inline source map URI)
+   */
+  encoding?: BufferEncoding
+}
+
+function parseSourceMap(opts: string | SourceMapOptions): SourceMap {
+  if (typeof opts === 'string') {
+    let lines = opts.trimEnd().split('\n')
+    let comment = lines.at(-1) ?? ''
+    let map = String(comment).match(SOURCE_MAP_COMMENT)?.[1] ?? null
+    if (!map) throw new Error('No source map comment found')
+
+    return parseSourceMap({
+      map,
+      content: lines.slice(0, -1).join('\n'),
+      encoding: 'base64',
+    })
+  }
+
+  let rawMap: RawSourceMap
+  let content = opts.content
+
+  if (typeof opts.map === 'object') {
+    rawMap = opts.map as RawSourceMap
+  } else {
+    rawMap = JSON.parse(Buffer.from(opts.map, opts.encoding ?? 'utf-8').toString())
+  }
+
+  let map = new SourceMapConsumer(rawMap)
+  let generatedTable = createLineTable(content)
+
+  return {
+    at(line: number, column: number) {
+      let pos = map.originalPositionFor({ line, column })
+      let source = pos.source ? map.sourceContentFor(pos.source) : null
+      let originalTable = createLineTable(source ?? '')
+      let originalOffset = originalTable.findOffset(pos)
+      let generatedOffset = generatedTable.findOffset({ line, column })
+
+      return {
+        source: pos.source,
+        original: source
+          ? source.slice(originalOffset, originalOffset + 10).trim() + '...'
+          : '(none)',
+        generated: content.slice(generatedOffset, generatedOffset + 10).trim() + '...',
+      }
+    },
+  }
+}

integrations/vite/source-maps.test.ts

@@ -0,0 +1,93 @@
+import { candidate, css, fetchStyles, html, json, retryAssertion, test, ts } from '../utils'
+
+test(
+  `dev build`,
+  {
+    fs: {
+      'package.json': json`
+        {
+          "type": "module",
+          "dependencies": {
+            "@tailwindcss/vite": "workspace:^",
+            "tailwindcss": "workspace:^"
+          },
+          "devDependencies": {
+            "lightningcss": "^1.26.0",
+            "vite": "^6"
+          }
+        }
+      `,
+      'vite.config.ts': ts`
+        import tailwindcss from '@tailwindcss/vite'
+        import { defineConfig } from 'vite'
+
+        export default defineConfig({
+          plugins: [tailwindcss()],
+          css: {
+            devSourcemap: true,
+          },
+        })
+      `,
+      'index.html': html`
+        <head>
+          <link rel="stylesheet" href="./src/index.css" />
+        </head>
+        <body>
+          <div class="flex">Hello, world!</div>
+        </body>
+      `,
+      'src/index.css': css`
+        @import 'tailwindcss/utilities';
+        /*  */
+      `,
+    },
+  },
+  async ({ fs, spawn, expect, parseSourceMap }) => {
+    // Source maps only work in development mode in Vite
+    let process = await spawn('pnpm vite dev')
+    await process.onStdout((m) => m.includes('ready in'))
+
+    let url = ''
+    await process.onStdout((m) => {
+      let match = /Local:\s*(http.*)\//.exec(m)
+      if (match) url = match[1]
+      return Boolean(url)
+    })
+
+    let styles = await retryAssertion(async () => {
+      let styles = await fetchStyles(url, '/index.html')
+
+      // Wait until we have the right CSS
+      expect(styles).toContain(candidate`flex`)
+
+      return styles
+    })
+
+    // Make sure we can find a source map
+    let map = parseSourceMap(styles)
+
+    expect(map.at(1, 0)).toMatchObject({
+      source: null,
+      original: '(none)',
+      generated: '/*! tailwi...',
+    })
+
+    expect(map.at(2, 0)).toMatchObject({
+      source: expect.stringContaining('node_modules/tailwindcss/utilities.css'),
+      original: '@tailwind...',
+      generated: '.flex {...',
+    })
+
+    expect(map.at(3, 2)).toMatchObject({
+      source: expect.stringContaining('node_modules/tailwindcss/utilities.css'),
+      original: '@tailwind...',
+      generated: 'display: f...',
+    })
+
+    expect(map.at(4, 0)).toMatchObject({
+      source: null,
+      original: '(none)',
+      generated: '}...',
+    })
+  },
+)

packages/@tailwindcss-browser/src/index.ts

@@ -116,6 +116,7 @@ async function loadStylesheet(id: string, base: string) {
   function load() {
     if (id === 'tailwindcss') {
       return {
+        path: 'virtual:tailwindcss/index.css',
         base,
         content: assets.css.index,
       }
@@ -125,6 +126,7 @@ async function loadStylesheet(id: string, base: string) {
       id === './preflight.css'
     ) {
       return {
+        path: 'virtual:tailwindcss/preflight.css',
         base,
         content: assets.css.preflight,
       }
@@ -134,6 +136,7 @@ async function loadStylesheet(id: string, base: string) {
       id === './theme.css'
     ) {
       return {
+        path: 'virtual:tailwindcss/theme.css',
         base,
         content: assets.css.theme,
       }
@@ -143,6 +146,7 @@ async function loadStylesheet(id: string, base: string) {
       id === './utilities.css'
     ) {
       return {
+        path: 'virtual:tailwindcss/utilities.css',
         base,
         content: assets.css.utilities,
       }

packages/@tailwindcss-cli/src/commands/build/index.ts

@@ -1,5 +1,12 @@
 import watcher from '@parcel/watcher'
-import { compile, env, Instrumentation, optimize } from '@tailwindcss/node'
+import {
+  compile,
+  env,
+  Instrumentation,
+  optimize,
+  toSourceMap,
+  type SourceMap,
+} from '@tailwindcss/node'
 import { clearRequireCache } from '@tailwindcss/node/require-cache'
 import { Scanner, type ChangedContent } from '@tailwindcss/oxide'
 import { existsSync, type Stats } from 'node:fs'
@@ -52,6 +59,11 @@ export function options() {
       description: 'The current working directory',
       default: '.',
     },
+    '--map': {
+      type: 'boolean | string',
+      description: 'Generate a source map',
+      default: false,
+    },
   } satisfies Arg
 }
 
@@ -105,6 +117,21 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
     process.exit(1)
   }
 
+  // If the user passes `{bin} build --map -` then this likely means they want to output the map inline
+  // this is the default behavior of `{bin build} --map` to inform the user of that
+  if (args['--map'] === '-') {
+    eprintln(header())
+    eprintln()
+    eprintln(`Use --map without a value to inline the source map`)
+    process.exit(1)
+  }
+
+  // Resolve the map as an absolute path. If the output is true then we
+  // don't need to resolve it because it'll be an inline source map
+  if (args['--map'] && args['--map'] !== true) {
+    args['--map'] = path.resolve(base, args['--map'])
+  }
+
   let start = process.hrtime.bigint()
 
   let input = args['--input']
@@ -120,27 +147,48 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
     optimizedCss: '',
   }
 
-  async function write(css: string, args: Result<ReturnType<typeof options>>, I: Instrumentation) {
+  async function write(
+    css: string,
+    map: SourceMap | null,
+    args: Result<ReturnType<typeof options>>,
+    I: Instrumentation,
+  ) {
     let output = css
 
     // Optimize the output
     if (args['--minify'] || args['--optimize']) {
       if (css !== previous.css) {
         DEBUG && I.start('Optimize CSS')
-        let optimizedCss = optimize(css, {
+        let optimized = optimize(css, {
           file: args['--input'] ?? 'input.css',
           minify: args['--minify'] ?? false,
+          map: map?.raw ?? undefined,
         })
         DEBUG && I.end('Optimize CSS')
         previous.css = css
-        previous.optimizedCss = optimizedCss
-        output = optimizedCss
+        previous.optimizedCss = optimized.code
+        if (optimized.map) {
+          map = toSourceMap(optimized.map)
+        }
+        output = optimized.code
       } else {
         output = previous.optimizedCss
       }
     }
 
     // Write the output
+    if (map) {
+      // Inline the source map
+      if (args['--map'] === true) {
+        output += `\n`
+        output += map.inline
+      } else if (typeof args['--map'] === 'string') {
+        DEBUG && I.start('Write source map')
+        await outputFile(args['--map'], map.raw)
+        DEBUG && I.end('Write source map')
+      }
+    }
+
     DEBUG && I.start('Write output')
     if (args['--output'] && args['--output'] !== '-') {
       await outputFile(args['--output'], output)
@@ -160,6 +208,7 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
   async function createCompiler(css: string, I: Instrumentation) {
     DEBUG && I.start('Setup compiler')
     let compiler = await compile(css, {
+      from: args['--output'] ? (inputFilePath ?? 'stdin.css') : undefined,
       base: inputBasePath,
       onDependency(path) {
         fullRebuildPaths.push(path)
@@ -231,6 +280,7 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
 
           // Track the compiled CSS
           let compiledCss = ''
+          let compiledMap: SourceMap | null = null
 
           // Scan the entire `base` directory for full rebuilds.
           if (rebuildStrategy === 'full') {
@@ -269,6 +319,12 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
             DEBUG && I.start('Build CSS')
             compiledCss = compiler.build(candidates)
             DEBUG && I.end('Build CSS')
+
+            if (args['--map']) {
+              DEBUG && I.start('Build Source Map')
+              compiledMap = compiler.buildSourceMap() as any
+              DEBUG && I.end('Build Source Map')
+            }
           }
 
           // Scan changed files only for incremental rebuilds.
@@ -288,9 +344,15 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
             DEBUG && I.start('Build CSS')
             compiledCss = compiler.build(newCandidates)
             DEBUG && I.end('Build CSS')
+
+            if (args['--map']) {
+              DEBUG && I.start('Build Source Map')
+              compiledMap = compiler.buildSourceMap() as any
+              DEBUG && I.end('Build Source Map')
+            }
           }
 
-          await write(compiledCss, args, I)
+          await write(compiledCss, compiledMap, args, I)
 
           let end = process.hrtime.bigint()
           eprintln(`Done in ${formatDuration(end - start)}`)
@@ -325,7 +387,16 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
   DEBUG && I.start('Build CSS')
   let output = await handleError(() => compiler.build(candidates))
   DEBUG && I.end('Build CSS')
-  await write(output, args, I)
+
+  let map: SourceMap | null = null
+
+  if (args['--map']) {
+    DEBUG && I.start('Build Source Map')
+    map = await handleError(() => toSourceMap(compiler.buildSourceMap()))
+    DEBUG && I.end('Build Source Map')
+  }
+
+  await write(output, map, args, I)
 
   let end = process.hrtime.bigint()
   eprintln(header())

packages/@tailwindcss-node/package.json

@@ -37,9 +37,12 @@
     }
   },
   "dependencies": {
+    "@ampproject/remapping": "^2.3.0",
     "enhanced-resolve": "^5.18.1",
     "jiti": "^2.4.2",
-    "tailwindcss": "workspace:*",
-    "lightningcss": "catalog:"
+    "lightningcss": "catalog:",
+    "magic-string": "^0.30.17",
+    "source-map-js": "^1.2.1",
+    "tailwindcss": "workspace:*"
   }
 }

packages/@tailwindcss-node/src/compile.ts

@@ -2,7 +2,7 @@ import EnhancedResolve from 'enhanced-resolve'
 import { createJiti, type Jiti } from 'jiti'
 import fs from 'node:fs'
 import fsPromises from 'node:fs/promises'
-import path, { dirname } from 'node:path'
+import path from 'node:path'
 import { pathToFileURL } from 'node:url'
 import {
   __unstable__loadDesignSystem as ___unstable__loadDesignSystem,
@@ -21,6 +21,7 @@ export type Resolver = (id: string, base: string) => Promise<string | false | un
 
 export interface CompileOptions {
   base: string
+  from?: string
   onDependency: (path: string) => void
   shouldRewriteUrls?: boolean
   polyfills?: Polyfills
@@ -31,6 +32,7 @@ export interface CompileOptions {
 
 function createCompileOptions({
   base,
+  from,
   polyfills,
   onDependency,
   shouldRewriteUrls,
@@ -41,6 +43,7 @@ function createCompileOptions({
   return {
     base,
     polyfills,
+    from,
     async loadModule(id: string, base: string) {
       return loadModule(id, base, onDependency, customJsResolver)
     },
@@ -125,7 +128,8 @@ export async function loadModule(
 
     let module = await importModule(pathToFileURL(resolvedPath).href)
     return {
-      base: dirname(resolvedPath),
+      path: resolvedPath,
+      base: path.dirname(resolvedPath),
       module: module.default ?? module,
     }
   }
@@ -144,7 +148,8 @@ export async function loadModule(
     onDependency(file)
   }
   return {
-    base: dirname(resolvedPath),
+    path: resolvedPath,
+    base: path.dirname(resolvedPath),
     module: module.default ?? module,
   }
 }
@@ -164,6 +169,7 @@ async function loadStylesheet(
     let file = await globalThis.__tw_readFile(resolvedPath, 'utf-8')
     if (file) {
       return {
+        path: resolvedPath,
         base: path.dirname(resolvedPath),
         content: file,
       }
@@ -172,6 +178,7 @@ async function loadStylesheet(
 
   let file = await fsPromises.readFile(resolvedPath, 'utf-8')
   return {
+    path: resolvedPath,
     base: path.dirname(resolvedPath),
     content: file,
   }

packages/@tailwindcss-node/src/index.cts

@@ -5,6 +5,7 @@ export * from './compile'
 export * from './instrumentation'
 export * from './normalize-path'
 export * from './optimize'
+export * from './source-maps'
 export { env }
 
 // In Bun, ESM modules will also populate `require.cache`, so the module hook is

packages/@tailwindcss-node/src/index.ts

@@ -5,6 +5,7 @@ export * from './compile'
 export * from './instrumentation'
 export * from './normalize-path'
 export * from './optimize'
+export * from './source-maps'
 export { env }
 
 // In Bun, ESM modules will also populate `require.cache`, so the module hook is

packages/@tailwindcss-node/src/optimize.ts

@@ -1,15 +1,42 @@
+import remapping from '@ampproject/remapping'
 import { Features, transform } from 'lightningcss'
+import MagicString from 'magic-string'
+
+export interface OptimizeOptions {
+  /**
+   * The file being transformed
+   */
+  file?: string
+
+  /**
+   * Enabled minified output
+   */
+  minify?: boolean
+
+  /**
+   * The output source map before optimization
+   *
+   * If omitted a resulting source map will not be available
+   */
+  map?: string
+}
+
+export interface TransformResult {
+  code: string
+  map: string | undefined
+}
 
 export function optimize(
   input: string,
-  { file = 'input.css', minify = false }: { file?: string; minify?: boolean } = {},
-): string {
-  function optimize(code: Buffer | Uint8Array) {
+  { file = 'input.css', minify = false, map }: OptimizeOptions = {},
+): TransformResult {
+  function optimize(code: Buffer | Uint8Array, map: string | undefined) {
     return transform({
       filename: file,
-      code: code as any,
+      code,
       minify,
-      sourceMap: false,
+      sourceMap: typeof map !== 'undefined',
+      inputSourceMap: map,
       drafts: {
         customMedia: true,
       },
@@ -25,16 +52,39 @@ export function optimize(
         chrome: 111 << 16,
       },
       errorRecovery: true,
-    }).code
+    })
   }
 
   // Running Lightning CSS twice to ensure that adjacent rules are merged after
   // nesting is applied. This creates a more optimized output.
-  let out = optimize(optimize(Buffer.from(input))).toString()
+  let result = optimize(Buffer.from(input), map)
+  map = result.map?.toString()
+
+  result = optimize(result.code, map)
+  map = result.map?.toString()
+
+  let code = result.code.toString()
 
   // Work around an issue where the media query range syntax transpilation
   // generates code that is invalid with `@media` queries level 3.
-  out = out.replaceAll('@media not (', '@media not all and (')
+  let magic = new MagicString(code)
+  magic.replaceAll('@media not (', '@media not all and (')
 
-  return out
+  // We have to use a source-map-preserving method of replacing the content
+  // which requires the use of Magic String + remapping(…) to make sure
+  // the resulting map is correct
+  if (map !== undefined && magic.hasChanged()) {
+    let magicMap = magic.generateMap({ source: 'original', hires: 'boundary' }).toString()
+
+    let remapped = remapping([magicMap, map], () => null)
+
+    map = remapped.toString()
+  }
+
+  code = magic.toString()
+
+  return {
+    code,
+    map,
+  }
 }

packages/@tailwindcss-node/src/source-maps.ts

@@ -0,0 +1,59 @@
+import { SourceMapGenerator } from 'source-map-js'
+import type { DecodedSource, DecodedSourceMap } from '../../tailwindcss/src/source-maps/source-map'
+import { DefaultMap } from '../../tailwindcss/src/utils/default-map'
+
+export type { DecodedSource, DecodedSourceMap }
+export interface SourceMap {
+  readonly raw: string
+  readonly inline: string
+}
+
+function serializeSourceMap(map: DecodedSourceMap): string {
+  let generator = new SourceMapGenerator()
+
+  let id = 1
+  let sourceTable = new DefaultMap<
+    DecodedSource | null,
+    {
+      url: string
+      content: string
+    }
+  >((src) => {
+    return {
+      url: src?.url ?? `<unknown ${id++}>`,
+      content: src?.content ?? '<none>',
+    }
+  })
+
+  for (let mapping of map.mappings) {
+    let original = sourceTable.get(mapping.originalPosition?.source ?? null)
+
+    generator.addMapping({
+      generated: mapping.generatedPosition,
+      original: mapping.originalPosition,
+      source: original.url,
+      name: mapping.name,
+    })
+
+    generator.setSourceContent(original.url, original.content)
+  }
+
+  return generator.toString()
+}
+
+export function toSourceMap(map: DecodedSourceMap | string): SourceMap {
+  let raw = typeof map === 'string' ? map : serializeSourceMap(map)
+
+  return {
+    raw,
+    get inline() {
+      let tmp = ''
+
+      tmp += '/*# sourceMappingURL=data:application/json;base64,'
+      tmp += Buffer.from(raw, 'utf-8').toString('base64')
+      tmp += ' */\n'
+
+      return tmp
+    },
+  }
+}

packages/@tailwindcss-postcss/src/ast.ts

@@ -1,17 +1,54 @@
 import postcss, {
+  Input,
   type ChildNode as PostCssChildNode,
   type Container as PostCssContainerNode,
   type Root as PostCssRoot,
   type Source as PostcssSource,
 } from 'postcss'
 import { atRule, comment, decl, rule, type AstNode } from '../../tailwindcss/src/ast'
+import { createLineTable, type LineTable } from '../../tailwindcss/src/source-maps/line-table'
+import type { Source, SourceLocation } from '../../tailwindcss/src/source-maps/source'
+import { DefaultMap } from '../../tailwindcss/src/utils/default-map'
 
 const EXCLAMATION_MARK = 0x21
 
 export function cssAstToPostCssAst(ast: AstNode[], source: PostcssSource | undefined): PostCssRoot {
+  let inputMap = new DefaultMap<Source, Input>((src) => {
+    return new Input(src.code, {
+      map: source?.input.map,
+      from: src.file ?? undefined,
+    })
+  })
+
+  let lineTables = new DefaultMap<Source, LineTable>((src) => createLineTable(src.code))
+
   let root = postcss.root()
   root.source = source
 
+  function toSource(loc: SourceLocation | undefined): PostcssSource | undefined {
+    // Use the fallback if this node has no location info in the AST
+    if (!loc) return
+    if (!loc[0]) return
+
+    let table = lineTables.get(loc[0])
+    let start = table.find(loc[1])
+    let end = table.find(loc[2])
+
+    return {
+      input: inputMap.get(loc[0]),
+      start: {
+        line: start.line,
+        column: start.column + 1,
+        offset: loc[1],
+      },
+      end: {
+        line: end.line,
+        column: end.column + 1,
+        offset: loc[2],
+      },
+    }
+  }
+
   function transform(node: AstNode, parent: PostCssContainerNode) {
     // Declaration
     if (node.kind === 'declaration') {
@@ -20,14 +57,14 @@ export function cssAstToPostCssAst(ast: AstNode[], source: PostcssSource | undef
         value: node.value ?? '',
         important: node.important,
       })
-      astNode.source = source
+      astNode.source = toSource(node.src)
       parent.append(astNode)
     }
 
     // Rule
     else if (node.kind === 'rule') {
       let astNode = postcss.rule({ selector: node.selector })
-      astNode.source = source
+      astNode.source = toSource(node.src)
       astNode.raws.semicolon = true
       parent.append(astNode)
       for (let child of node.nodes) {
@@ -38,7 +75,7 @@ export function cssAstToPostCssAst(ast: AstNode[], source: PostcssSource | undef
     // AtRule
     else if (node.kind === 'at-rule') {
       let astNode = postcss.atRule({ name: node.name.slice(1), params: node.params })
-      astNode.source = source
+      astNode.source = toSource(node.src)
       astNode.raws.semicolon = true
       parent.append(astNode)
       for (let child of node.nodes) {
@@ -53,7 +90,7 @@ export function cssAstToPostCssAst(ast: AstNode[], source: PostcssSource | undef
       // spaces.
       astNode.raws.left = ''
       astNode.raws.right = ''
-      astNode.source = source
+      astNode.source = toSource(node.src)
       parent.append(astNode)
     }
 
@@ -75,18 +112,38 @@ export function cssAstToPostCssAst(ast: AstNode[], source: PostcssSource | undef
 }
 
 export function postCssAstToCssAst(root: PostCssRoot): AstNode[] {
+  let inputMap = new DefaultMap<Input, Source>((input) => ({
+    file: input.file ?? input.id ?? null,
+    code: input.css,
+  }))
+
+  function toSource(node: PostCssChildNode): SourceLocation | undefined {
+    let source = node.source
+    if (!source) return
+
+    let input = source.input
+    if (!input) return
+    if (source.start === undefined) return
+    if (source.end === undefined) return
+
+    return [inputMap.get(input), source.start.offset, source.end.offset]
+  }
+
   function transform(
     node: PostCssChildNode,
     parent: Extract<AstNode, { nodes: AstNode[] }>['nodes'],
   ) {
     // Declaration
     if (node.type === 'decl') {
-      parent.push(decl(node.prop, node.value, node.important))
+      let astNode = decl(node.prop, node.value, node.important)
+      astNode.src = toSource(node)
+      parent.push(astNode)
     }
 
     // Rule
     else if (node.type === 'rule') {
       let astNode = rule(node.selector)
+      astNode.src = toSource(node)
       node.each((child) => transform(child, astNode.nodes))
       parent.push(astNode)
     }
@@ -94,6 +151,7 @@ export function postCssAstToCssAst(root: PostCssRoot): AstNode[] {
     // AtRule
     else if (node.type === 'atrule') {
       let astNode = atRule(`@${node.name}`, node.params)
+      astNode.src = toSource(node)
       node.each((child) => transform(child, astNode.nodes))
       parent.push(astNode)
     }
@@ -101,7 +159,9 @@ export function postCssAstToCssAst(root: PostCssRoot): AstNode[] {
     // Comment
     else if (node.type === 'comment') {
       if (node.text.charCodeAt(0) !== EXCLAMATION_MARK) return
-      parent.push(comment(node.text))
+      let astNode = comment(node.text)
+      astNode.src = toSource(node)
+      parent.push(astNode)
     }
 
     // Unknown

packages/@tailwindcss-postcss/src/index.ts

@@ -121,6 +121,7 @@ function tailwindcss(opts: PluginOptions = {}): AcceptedPlugin {
 
             DEBUG && I.start('Create compiler')
             let compiler = await compileAst(ast, {
+              from: result.opts.from,
               base: inputBasePath,
               shouldRewriteUrls: true,
               onDependency: (path) => context.fullRebuildPaths.push(path),
@@ -282,13 +283,13 @@ function tailwindcss(opts: PluginOptions = {}): AcceptedPlugin {
                 DEBUG && I.end('AST -> CSS')
 
                 DEBUG && I.start('Lightning CSS')
-                let ast = optimizeCss(css, {
+                let optimized = optimizeCss(css, {
                   minify: typeof optimize === 'object' ? optimize.minify : true,
                 })
                 DEBUG && I.end('Lightning CSS')
 
                 DEBUG && I.start('CSS -> PostCSS AST')
-                context.optimizedPostCssAst = postcss.parse(ast, result.opts)
+                context.optimizedPostCssAst = postcss.parse(optimized.code, result.opts)
                 DEBUG && I.end('CSS -> PostCSS AST')
 
                 DEBUG && I.end('Optimization')

packages/@tailwindcss-vite/src/index.ts

@@ -1,4 +1,12 @@
-import { compile, env, Features, Instrumentation, normalizePath, optimize } from '@tailwindcss/node'
+import {
+  compile,
+  env,
+  Features,
+  Instrumentation,
+  normalizePath,
+  optimize,
+  toSourceMap,
+} from '@tailwindcss/node'
 import { clearRequireCache } from '@tailwindcss/node/require-cache'
 import { Scanner } from '@tailwindcss/oxide'
 import fs from 'node:fs/promises'
@@ -34,7 +42,15 @@ export default function tailwindcss(): Plugin[] {
     function customJsResolver(id: string, base: string) {
       return jsResolver(id, base, true, isSSR)
     }
-    return new Root(id, config!.root, customCssResolver, customJsResolver)
+    return new Root(
+      id,
+      config!.root,
+      // Currently, Vite only supports CSS source maps in development and they
+      // are off by default. Check to see if we need them or not.
+      config?.css.devSourcemap ?? false,
+      customCssResolver,
+      customJsResolver,
+    )
   })
 
   return [
@@ -68,14 +84,14 @@ export default function tailwindcss(): Plugin[] {
 
         let root = roots.get(id)
 
-        let generated = await root.generate(src, (file) => this.addWatchFile(file), I)
-        if (!generated) {
+        let result = await root.generate(src, (file) => this.addWatchFile(file), I)
+        if (!result) {
           roots.delete(id)
           return src
         }
 
         DEBUG && I.end('[@tailwindcss/vite] Generate CSS (serve)')
-        return { code: generated }
+        return result
       },
     },
 
@@ -93,18 +109,21 @@ export default function tailwindcss(): Plugin[] {
 
         let root = roots.get(id)
 
-        let generated = await root.generate(src, (file) => this.addWatchFile(file), I)
-        if (!generated) {
+        let result = await root.generate(src, (file) => this.addWatchFile(file), I)
+        if (!result) {
           roots.delete(id)
           return src
         }
         DEBUG && I.end('[@tailwindcss/vite] Generate CSS (build)')
 
         DEBUG && I.start('[@tailwindcss/vite] Optimize CSS')
-        generated = optimize(generated, { minify })
+        result = optimize(result.code, {
+          minify,
+          map: result.map,
+        })
         DEBUG && I.end('[@tailwindcss/vite] Optimize CSS')
 
-        return { code: generated }
+        return result
       },
     },
   ] satisfies Plugin[]
@@ -173,6 +192,7 @@ class Root {
     private id: string,
     private base: string,
 
+    private enableSourceMaps: boolean,
     private customCssResolver: (id: string, base: string) => Promise<string | false | undefined>,
     private customJsResolver: (id: string, base: string) => Promise<string | false | undefined>,
   ) {}
@@ -183,7 +203,13 @@ class Root {
     content: string,
     _addWatchFile: (file: string) => void,
     I: Instrumentation,
-  ): Promise<string | false> {
+  ): Promise<
+    | {
+        code: string
+        map: string | undefined
+      }
+    | false
+  > {
     let inputPath = idToPath(this.id)
 
     function addWatchFile(file: string) {
@@ -215,6 +241,7 @@ class Root {
       DEBUG && I.start('Setup compiler')
       let addBuildDependenciesPromises: Promise<void>[] = []
       this.compiler = await compile(content, {
+        from: this.enableSourceMaps ? this.id : undefined,
         base: inputBase,
         shouldRewriteUrls: true,
         onDependency: (path) => {
@@ -313,10 +340,17 @@ class Root {
     }
 
     DEBUG && I.start('Build CSS')
-    let result = this.compiler.build([...this.candidates])
+    let code = this.compiler.build([...this.candidates])
     DEBUG && I.end('Build CSS')
 
-    return result
+    DEBUG && I.start('Build Source Map')
+    let map = this.enableSourceMaps ? toSourceMap(this.compiler.buildSourceMap()).raw : undefined
+    DEBUG && I.end('Build Source Map')
+
+    return {
+      code,
+      map,
+    }
   }
 
   private async addBuildDependency(path: string) {

packages/tailwindcss/package.json

@@ -127,9 +127,12 @@
     "utilities.css"
   ],
   "devDependencies": {
+    "@ampproject/remapping": "^2.3.0",
     "@tailwindcss/oxide": "workspace:^",
     "@types/node": "catalog:",
+    "dedent": "1.5.3",
     "lightningcss": "catalog:",
-    "dedent": "1.5.3"
+    "magic-string": "^0.30.17",
+    "source-map-js": "^1.2.1"
   }
 }

packages/tailwindcss/src/apply.ts

@@ -2,6 +2,7 @@ import { Features } from '.'
 import { rule, toCss, walk, WalkAction, type AstNode } from './ast'
 import { compileCandidates } from './compile'
 import type { DesignSystem } from './design-system'
+import type { SourceLocation } from './source-maps/source'
 import { DefaultMap } from './utils/default-map'
 
 export function substituteAtApply(ast: AstNode[], designSystem: DesignSystem) {
@@ -155,17 +156,59 @@ export function substituteAtApply(ast: AstNode[], designSystem: DesignSystem) {
       let node = parent.nodes[i]
       if (node.kind !== 'at-rule' || node.name !== '@apply') continue
 
-      let candidates = node.params.split(/\s+/g)
+      let parts = node.params.split(/(\s+)/g)
+      let candidateOffsets: Record<string, number> = {}
+
+      let offset = 0
+      for (let [idx, part] of parts.entries()) {
+        if (idx % 2 === 0) candidateOffsets[part] = offset
+        offset += part.length
+      }
 
       // Replace the `@apply` rule with the actual utility classes
       {
         // Parse the candidates to an AST that we can replace the `@apply` rule
         // with.
-        let candidateAst = compileCandidates(candidates, designSystem, {
+        let candidates = Object.keys(candidateOffsets)
+        let compiled = compileCandidates(candidates, designSystem, {
           onInvalidCandidate: (candidate) => {
             throw new Error(`Cannot apply unknown utility class: ${candidate}`)
           },
-        }).astNodes
+        })
+
+        let src = node.src
+
+        let candidateAst = compiled.astNodes.map((node) => {
+          let candidate = compiled.nodeSorting.get(node)?.candidate
+          let candidateOffset = candidate ? candidateOffsets[candidate] : undefined
+
+          node = structuredClone(node)
+
+          if (!src || !candidate || candidateOffset === undefined) {
+            // While the original nodes may have come from an `@utility` we still
+            // want to replace the source because the `@apply` is ultimately the
+            // reason the node was emitted into the AST.
+            walk([node], (node) => {
+              node.src = src
+            })
+
+            return node
+          }
+
+          let candidateSrc: SourceLocation = [src[0], src[1], src[2]]
+
+          candidateSrc[1] += 7 /* '@apply '.length */ + candidateOffset
+          candidateSrc[2] = candidateSrc[1] + candidate.length
+
+          // While the original nodes may have come from an `@utility` we still
+          // want to replace the source because the `@apply` is ultimately the
+          // reason the node was emitted into the AST.
+          walk([node], (node) => {
+            node.src = candidateSrc
+          })
+
+          return node
+        })
 
         // Collect the nodes to insert in place of the `@apply` rule. When a rule
         // was used, we want to insert its children instead of the rule because we

packages/tailwindcss/src/ast.bench.ts

@@ -0,0 +1,28 @@
+import { bench } from 'vitest'
+import { toCss } from './ast'
+import * as CSS from './css-parser'
+
+const css = String.raw
+const input = css`
+  @theme {
+    --color-primary: #333;
+  }
+  @tailwind utilities;
+  .foo {
+    color: red;
+    /* comment */
+    &:hover {
+      color: blue;
+      @apply font-bold;
+    }
+  }
+`
+const ast = CSS.parse(input)
+
+bench('toCss', () => {
+  toCss(ast)
+})
+
+bench('toCss with source maps', () => {
+  toCss(ast, true)
+})

packages/tailwindcss/src/ast.ts

@@ -1,6 +1,7 @@
 import { Polyfills } from '.'
 import { parseAtRule } from './css-parser'
 import type { DesignSystem } from './design-system'
+import type { Source, SourceLocation } from './source-maps/source'
 import { Theme, ThemeOptions } from './theme'
 import { DefaultMap } from './utils/default-map'
 import { extractUsedVariables } from './utils/variables'
@@ -12,6 +13,9 @@ export type StyleRule = {
   kind: 'rule'
   selector: string
   nodes: AstNode[]
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type AtRule = {
@@ -19,6 +23,9 @@ export type AtRule = {
   name: string
   params: string
   nodes: AstNode[]
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type Declaration = {
@@ -26,22 +33,34 @@ export type Declaration = {
   property: string
   value: string | undefined
   important: boolean
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type Comment = {
   kind: 'comment'
   value: string
+
+  src?: SourceLocation
+  dst?: SourceLocation
 }
 
 export type Context = {
   kind: 'context'
   context: Record<string, string | boolean>
   nodes: AstNode[]
+
+  src?: undefined
+  dst?: undefined
 }
 
 export type AtRoot = {
   kind: 'at-root'
   nodes: AstNode[]
+
+  src?: undefined
+  dst?: undefined
 }
 
 export type Rule = StyleRule | AtRule
@@ -378,10 +397,13 @@ export function optimizeAst(
           }
         }
 
+        let fallback = decl(property, initialValue ?? 'initial')
+        fallback.src = node.src
+
         if (inherits) {
-          propertyFallbacksRoot.push(decl(property, initialValue ?? 'initial'))
+          propertyFallbacksRoot.push(fallback)
         } else {
-          propertyFallbacksUniversal.push(decl(property, initialValue ?? 'initial'))
+          propertyFallbacksUniversal.push(fallback)
         }
       }
 
@@ -623,6 +645,7 @@ export function optimizeAst(
           value: ValueParser.toCss(ast),
         }
         let colorMixQuery = rule('@supports (color: color-mix(in lab, red, red))', [declaration])
+        colorMixQuery.src = declaration.src
         parent.splice(idx, 1, fallback, colorMixQuery)
       }
     }
@@ -632,11 +655,15 @@ export function optimizeAst(
     let fallbackAst = []
 
     if (propertyFallbacksRoot.length > 0) {
-      fallbackAst.push(rule(':root, :host', propertyFallbacksRoot))
+      let wrapper = rule(':root, :host', propertyFallbacksRoot)
+      wrapper.src = propertyFallbacksRoot[0].src
+      fallbackAst.push(wrapper)
     }
 
     if (propertyFallbacksUniversal.length > 0) {
-      fallbackAst.push(rule('*, ::before, ::after, ::backdrop', propertyFallbacksUniversal))
+      let wrapper = rule('*, ::before, ::after, ::backdrop', propertyFallbacksUniversal)
+      wrapper.src = propertyFallbacksUniversal[0].src
+      fallbackAst.push(wrapper)
     }
 
     if (fallbackAst.length > 0) {
@@ -658,30 +685,43 @@ export function optimizeAst(
         return true
       })
 
+      let layerPropertiesStatement = atRule('@layer', 'properties', [])
+      layerPropertiesStatement.src = fallbackAst[0].src
+
       newAst.splice(
         firstValidNodeIndex < 0 ? newAst.length : firstValidNodeIndex,
         0,
-        atRule('@layer', 'properties', []),
+        layerPropertiesStatement,
       )
 
-      newAst.push(
-        rule('@layer properties', [
-          atRule(
-            '@supports',
-            // We can't write a supports query for `@property` directly so we have to test for
-            // features that are added around the same time in Mozilla and Safari.
-            '((-webkit-hyphens: none) and (not (margin-trim: inline))) or ((-moz-orient: inline) and (not (color:rgb(from red r g b))))',
-            fallbackAst,
-          ),
-        ]),
-      )
+      let block = rule('@layer properties', [
+        atRule(
+          '@supports',
+          // We can't write a supports query for `@property` directly so we have to test for
+          // features that are added around the same time in Mozilla and Safari.
+          '((-webkit-hyphens: none) and (not (margin-trim: inline))) or ((-moz-orient: inline) and (not (color:rgb(from red r g b))))',
+          fallbackAst,
+        ),
+      ])
+
+      block.src = fallbackAst[0].src
+      block.nodes[0].src = fallbackAst[0].src
+
+      newAst.push(block)
     }
   }
 
   return newAst
 }
 
-export function toCss(ast: AstNode[]) {
+export function toCss(ast: AstNode[], track?: boolean) {
+  let pos = 0
+
+  let source: Source = {
+    file: null,
+    code: '',
+  }
+
   function stringify(node: AstNode, depth = 0): string {
     let css = ''
     let indent = '  '.repeat(depth)
@@ -689,15 +729,70 @@ export function toCss(ast: AstNode[]) {
     // Declaration
     if (node.kind === 'declaration') {
       css += `${indent}${node.property}: ${node.value}${node.important ? ' !important' : ''};\n`
+
+      if (track) {
+        // indent
+        pos += indent.length
+
+        // node.property
+        let start = pos
+        pos += node.property.length
+
+        // `: `
+        pos += 2
+
+        // node.value
+        pos += node.value?.length ?? 0
+
+        // !important
+        if (node.important) {
+          pos += 11
+        }
+
+        let end = pos
+
+        // `;\n`
+        pos += 2
+
+        node.dst = [source, start, end]
+      }
     }
 
     // Rule
     else if (node.kind === 'rule') {
       css += `${indent}${node.selector} {\n`
+
+      if (track) {
+        // indent
+        pos += indent.length
+
+        // node.selector
+        let start = pos
+        pos += node.selector.length
+
+        // ` `
+        pos += 1
+
+        let end = pos
+        node.dst = [source, start, end]
+
+        // `{\n`
+        pos += 2
+      }
+
       for (let child of node.nodes) {
         css += stringify(child, depth + 1)
       }
+
       css += `${indent}}\n`
+
+      if (track) {
+        // indent
+        pos += indent.length
+
+        // `}\n`
+        pos += 2
+      }
     }
 
     // AtRule
@@ -710,22 +805,97 @@ export function toCss(ast: AstNode[]) {
       // @layer base, components, utilities;
       // ```
       if (node.nodes.length === 0) {
-        return `${indent}${node.name} ${node.params};\n`
+        let css = `${indent}${node.name} ${node.params};\n`
+
+        if (track) {
+          // indent
+          pos += indent.length
+
+          // node.name
+          let start = pos
+          pos += node.name.length
+
+          // ` `
+          pos += 1
+
+          // node.params
+          pos += node.params.length
+          let end = pos
+
+          // `;\n`
+          pos += 2
+
+          node.dst = [source, start, end]
+        }
+
+        return css
       }
 
       css += `${indent}${node.name}${node.params ? ` ${node.params} ` : ' '}{\n`
+
+      if (track) {
+        // indent
+        pos += indent.length
+
+        // node.name
+        let start = pos
+        pos += node.name.length
+
+        if (node.params) {
+          // ` `
+          pos += 1
+
+          // node.params
+          pos += node.params.length
+        }
+
+        // ` `
+        pos += 1
+
+        let end = pos
+        node.dst = [source, start, end]
+
+        // `{\n`
+        pos += 2
+      }
+
       for (let child of node.nodes) {
         css += stringify(child, depth + 1)
       }
+
       css += `${indent}}\n`
+
+      if (track) {
+        // indent
+        pos += indent.length
+
+        // `}\n`
+        pos += 2
+      }
     }
 
     // Comment
     else if (node.kind === 'comment') {
       css += `${indent}/*${node.value}*/\n`
+
+      if (track) {
+        // indent
+        pos += indent.length
+
+        // The comment itself. We do this instead of just the inside because
+        // it seems more useful to have the entire comment span tracked.
+        let start = pos
+        pos += 2 + node.value.length + 2
+        let end = pos
+
+        node.dst = [source, start, end]
+
+        // `\n`
+        pos += 1
+      }
     }
 
-    // These should've been handled already by `prepareAstForPrinting` which
+    // These should've been handled already by `optimizeAst` which
     // means we can safely ignore them here. We return an empty string
     // immediately to signal that something went wrong.
     else if (node.kind === 'context' || node.kind === 'at-root') {
@@ -743,12 +913,11 @@ export function toCss(ast: AstNode[]) {
   let css = ''
 
   for (let node of ast) {
-    let result = stringify(node)
-    if (result !== '') {
-      css += result
-    }
+    css += stringify(node, 0)
   }
 
+  source.code = css
+
   return css
 }
 

packages/tailwindcss/src/at-import.ts

@@ -3,13 +3,21 @@ import { atRule, context, walk, WalkAction, type AstNode } from './ast'
 import * as CSS from './css-parser'
 import * as ValueParser from './value-parser'
 
-type LoadStylesheet = (id: string, basedir: string) => Promise<{ base: string; content: string }>
+type LoadStylesheet = (
+  id: string,
+  basedir: string,
+) => Promise<{
+  path: string
+  base: string
+  content: string
+}>
 
 export async function substituteAtImports(
   ast: AstNode[],
   base: string,
   loadStylesheet: LoadStylesheet,
   recurseCount = 0,
+  track = false,
 ) {
   let features = Features.None
   let promises: Promise<void>[] = []
@@ -45,10 +53,11 @@ export async function substituteAtImports(
           }
 
           let loaded = await loadStylesheet(uri, base)
-          let ast = CSS.parse(loaded.content)
-          await substituteAtImports(ast, loaded.base, loadStylesheet, recurseCount + 1)
+          let ast = CSS.parse(loaded.content, { from: track ? loaded.path : undefined })
+          await substituteAtImports(ast, loaded.base, loadStylesheet, recurseCount + 1, track)
 
           contextNode.nodes = buildImportNodes(
+            node,
             [context({ base: loaded.base }, ast)],
             layer,
             media,
@@ -140,6 +149,7 @@ export function parseImportParams(params: ValueParser.ValueAstNode[]) {
 }
 
 function buildImportNodes(
+  importNode: AstNode,
   importedAst: AstNode[],
   layer: string | null,
   media: string | null,
@@ -148,15 +158,21 @@ function buildImportNodes(
   let root = importedAst
 
   if (layer !== null) {
-    root = [atRule('@layer', layer, root)]
+    let node = atRule('@layer', layer, root)
+    node.src = importNode.src
+    root = [node]
   }
 
   if (media !== null) {
-    root = [atRule('@media', media, root)]
+    let node = atRule('@media', media, root)
+    node.src = importNode.src
+    root = [node]
   }
 
   if (supports !== null) {
-    root = [atRule('@supports', supports[0] === '(' ? supports : `(${supports})`, root)]
+    let node = atRule('@supports', supports[0] === '(' ? supports : `(${supports})`, root)
+    node.src = importNode.src
+    root = [node]
   }
 
   return root

packages/tailwindcss/src/compat/apply-compat-hooks.ts

@@ -30,7 +30,11 @@ export async function applyCompatibilityHooks({
     path: string,
     base: string,
     resourceHint: 'plugin' | 'config',
-  ) => Promise<{ module: any; base: string }>
+  ) => Promise<{
+    path: string
+    base: string
+    module: any
+  }>
   sources: { base: string; pattern: string; negated: boolean }[]
 }) {
   let features = Features.None

packages/tailwindcss/src/compat/config.test.ts

@@ -1156,6 +1156,7 @@ test('utilities must be prefixed', async () => {
 
   let compiler = await compile(input, {
     loadModule: async (id, base) => ({
+      path: '',
       base,
       module: { prefix: 'tw' },
     }),
@@ -1183,6 +1184,7 @@ test('utilities must be prefixed', async () => {
   // Non-prefixed utilities are ignored
   compiler = await compile(input, {
     loadModule: async (id, base) => ({
+      path: '',
       base,
       module: { prefix: 'tw' },
     }),
@@ -1202,6 +1204,7 @@ test('utilities used in @apply must be prefixed', async () => {
     `,
     {
       loadModule: async (id, base) => ({
+        path: '',
         base,
         module: { prefix: 'tw' },
       }),
@@ -1228,6 +1231,7 @@ test('utilities used in @apply must be prefixed', async () => {
       `,
       {
         loadModule: async (id, base) => ({
+          path: '',
           base,
           module: { prefix: 'tw' },
         }),
@@ -1258,6 +1262,7 @@ test('Prefixes configured in CSS take precedence over those defined in JS config
     {
       async loadModule(id, base) {
         return {
+          path: '',
           base,
           module: { prefix: 'tw' },
         }
@@ -1282,6 +1287,7 @@ test('a prefix must be letters only', async () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: { prefix: '__' },
           }
@@ -1305,6 +1311,7 @@ test('important: `#app`', async () => {
 
   let compiler = await compile(input, {
     loadModule: async (_, base) => ({
+      path: '',
       base,
       module: { important: '#app' },
     }),
@@ -1342,6 +1349,7 @@ test('important: true', async () => {
 
   let compiler = await compile(input, {
     loadModule: async (_, base) => ({
+      path: '',
       base,
       module: { important: true },
     }),
@@ -1378,6 +1386,7 @@ test('blocklisted candidates are not generated', async () => {
     {
       async loadModule(id, base) {
         return {
+          path: '',
           base,
           module: {
             blocklist: ['bg-white'],
@@ -1421,6 +1430,7 @@ test('blocklisted candidates cannot be used with `@apply`', async () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: {
               blocklist: ['bg-white'],
@@ -1473,6 +1483,7 @@ test('old theme values are merged with their renamed counterparts in the CSS the
     {
       async loadModule(id, base) {
         return {
+          path: '',
           base,
           module: plugin(function ({ theme }) {
             didCallPluginFn()

packages/tailwindcss/src/compat/plugin-api.test.ts

@@ -17,6 +17,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ addBase, theme }) {
@@ -80,6 +81,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(function ({ addUtilities, theme }) {
             addUtilities({
@@ -116,6 +118,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -164,6 +167,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -211,6 +215,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -265,6 +270,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(function ({ addUtilities, theme }) {
             addUtilities({
@@ -313,6 +319,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ addUtilities, theme }) {
@@ -398,6 +405,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -452,6 +460,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -499,6 +508,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(function ({ matchUtilities, theme }) {
             matchUtilities(
@@ -557,6 +567,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -611,6 +622,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -660,6 +672,7 @@ describe('theme', async () => {
     await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ theme }) {
@@ -695,6 +708,7 @@ describe('theme', async () => {
     let { build } = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(function ({ matchUtilities, theme }) {
             function utility(name: string, themeKey: string) {
@@ -942,6 +956,7 @@ describe('theme', async () => {
     await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             ({ theme }) => {
@@ -984,6 +999,7 @@ describe('theme', async () => {
     await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(({ theme }) => {
             fn(theme('transitionTimingFunction.DEFAULT'))
@@ -1015,6 +1031,7 @@ describe('theme', async () => {
     await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(({ theme }) => {
             fn(theme('color.red.100'))
@@ -1043,6 +1060,7 @@ describe('theme', async () => {
     await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(({ theme }) => {
             fn(theme('i.do.not.exist'))
@@ -1069,6 +1087,7 @@ describe('theme', async () => {
     let { build } = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(({ addUtilities, matchUtilities }) => {
             addUtilities({
@@ -1124,6 +1143,7 @@ describe('theme', async () => {
     let { build } = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(function ({ matchUtilities }) {
             function utility(name: string, themeKey: string) {
@@ -1342,6 +1362,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -1400,6 +1421,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(function ({ matchUtilities, theme }) {
             matchUtilities(
@@ -1446,6 +1468,7 @@ describe('theme', async () => {
     let compiler = await compile(input, {
       loadModule: async (id, base) => {
         return {
+          path: '',
           base,
           module: plugin(
             function ({ matchUtilities, theme }) {
@@ -1493,6 +1516,7 @@ describe('addBase', () => {
       loadModule: async (id, base) => {
         if (id === 'inside') {
           return {
+            path: '',
             base,
             module: plugin(function ({ addBase }) {
               addBase({ inside: { color: 'red' } })
@@ -1500,6 +1524,7 @@ describe('addBase', () => {
           }
         }
         return {
+          path: '',
           base,
           module: plugin(function ({ addBase }) {
             addBase({ outside: { color: 'red' } })
@@ -1508,10 +1533,11 @@ describe('addBase', () => {
       },
       async loadStylesheet() {
         return {
+          path: '',
+          base: '',
           content: css`
             @plugin "inside";
           `,
-          base: '',
         }
       },
     })
@@ -1533,6 +1559,8 @@ describe('addBase', () => {
 
     let compiler = await compile(input, {
       loadModule: async () => ({
+        path: '',
+        base: '/root',
         module: plugin(function ({ addBase }) {
           addBase({
             ':root': {
@@ -1542,7 +1570,6 @@ describe('addBase', () => {
             },
           })
         }),
-        base: '/root',
       }),
     })
 
@@ -1571,6 +1598,7 @@ describe('addVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', '&:hover, &:focus')
@@ -1605,6 +1633,7 @@ describe('addVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', ['&:hover', '&:focus'])
@@ -1640,6 +1669,7 @@ describe('addVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', {
@@ -1677,6 +1707,7 @@ describe('addVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', {
@@ -1728,6 +1759,7 @@ describe('addVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ addVariant }: PluginAPI) => {
               addVariant(
@@ -1769,6 +1801,7 @@ describe('addVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', {
@@ -1811,6 +1844,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('potato', (flavor) => `.potato-${flavor} &`)
@@ -1845,6 +1879,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('potato', (flavor) => `@media (potato: ${flavor})`)
@@ -1883,6 +1918,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant(
@@ -1929,6 +1965,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('tooltip', (side) => `&${side}`, {
@@ -1968,6 +2005,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('alphabet', (side) => `&${side}`, {
@@ -2010,6 +2048,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('test', (selector) =>
@@ -2042,6 +2081,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('testmin', (value) => `@media (min-width: ${value})`, {
@@ -2094,6 +2134,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('testmin', (value) => `@media (min-width: ${value})`, {
@@ -2149,6 +2190,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('testmin', (value) => `@media (min-width: ${value})`, {
@@ -2221,6 +2263,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('testmin', (value) => `@media (min-width: ${value})`, {
@@ -2275,6 +2318,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('testmin', (value) => `@media (min-width: ${value})`, {
@@ -2347,6 +2391,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('testmin', (value) => `@media (min-width: ${value})`, {
@@ -2415,6 +2460,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('testmin', (value) => `@media (min-width: ${value})`, {
@@ -2495,6 +2541,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('foo', (value) => `.foo${value} &`, {
@@ -2529,6 +2576,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('foo', (value) => `.foo${value} &`)
@@ -2553,6 +2601,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('foo', (value) => `.foo${value === null ? '-good' : '-bad'} &`, {
@@ -2585,6 +2634,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('foo', (value) => `.foo${value === undefined ? '-good' : '-bad'} &`, {
@@ -2615,6 +2665,7 @@ describe('matchVariant', () => {
       {
         loadModule: async (id, base) => {
           return {
+            path: '',
             base,
             module: ({ matchVariant }: PluginAPI) => {
               matchVariant('my-container', (value, { modifier }) => {
@@ -2669,6 +2720,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -2710,6 +2762,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities([
@@ -2743,6 +2796,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities([
@@ -2782,6 +2836,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities([
@@ -2816,6 +2871,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -2857,6 +2913,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -2913,6 +2970,7 @@ describe('addUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ addUtilities }: PluginAPI) => {
                 addUtilities({
@@ -2942,6 +3000,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -2985,6 +3044,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -3026,6 +3086,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -3122,6 +3183,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -3175,6 +3237,7 @@ describe('addUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addUtilities }: PluginAPI) => {
               addUtilities({
@@ -3240,6 +3303,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities(
@@ -3320,6 +3384,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities(
@@ -3361,6 +3426,7 @@ describe('matchUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ matchUtilities }: PluginAPI) => {
               matchUtilities(
@@ -3410,6 +3476,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities(
@@ -3480,6 +3547,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities(
@@ -3554,6 +3622,7 @@ describe('matchUtilities()', () => {
           {
             async loadModule(id, base) {
               return {
+                path: '',
                 base,
                 module: ({ matchUtilities }: PluginAPI) => {
                   matchUtilities(
@@ -3609,6 +3678,7 @@ describe('matchUtilities()', () => {
           {
             async loadModule(id, base) {
               return {
+                path: '',
                 base,
                 module: ({ matchUtilities }: PluginAPI) => {
                   matchUtilities(
@@ -3647,6 +3717,7 @@ describe('matchUtilities()', () => {
           {
             async loadModule(id, base) {
               return {
+                path: '',
                 base,
                 module: ({ matchUtilities }: PluginAPI) => {
                   matchUtilities(
@@ -3691,6 +3762,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities(
@@ -3818,6 +3890,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities(
@@ -3903,6 +3976,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities(
@@ -3961,6 +4035,7 @@ describe('matchUtilities()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ matchUtilities }: PluginAPI) => {
               matchUtilities(
@@ -4028,6 +4103,7 @@ describe('matchUtilities()', () => {
         {
           async loadModule(id, base) {
             return {
+              path: '',
               base,
               module: ({ matchUtilities }: PluginAPI) => {
                 matchUtilities({
@@ -4056,6 +4132,7 @@ describe('matchUtilities()', () => {
       {
         async loadModule(base) {
           return {
+            path: '',
             base,
             module: ({ matchUtilities }: PluginAPI) => {
               matchUtilities(
@@ -4122,6 +4199,7 @@ describe('addComponents()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ addComponents }: PluginAPI) => {
               addComponents({
@@ -4190,6 +4268,7 @@ describe('matchComponents()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ matchComponents }: PluginAPI) => {
               matchComponents(
@@ -4235,6 +4314,7 @@ describe('prefix()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ prefix }: PluginAPI) => {
               fn(prefix('btn'))
@@ -4258,6 +4338,7 @@ describe('config()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ config }: PluginAPI) => {
               fn(config())
@@ -4285,6 +4366,7 @@ describe('config()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ config }: PluginAPI) => {
               fn(config('theme'))
@@ -4310,6 +4392,7 @@ describe('config()', () => {
       {
         async loadModule(id, base) {
           return {
+            path: '',
             base,
             module: ({ config }: PluginAPI) => {
               fn(config('somekey', 'defaultvalue'))

packages/tailwindcss/src/css-functions.test.ts

@@ -412,8 +412,9 @@ describe('--theme(…)', () => {
         [],
         {
           loadModule: async () => ({
-            module: () => {},
+            path: '',
             base: '/root',
+            module: () => {},
           }),
         },
       ),
@@ -771,7 +772,11 @@ describe('theme(…)', () => {
               }
             `,
             {
-              loadModule: async () => ({ module: {}, base: '/root' }),
+              loadModule: async () => ({
+                path: '',
+                base: '/root',
+                module: {},
+              }),
             },
           )
 
@@ -1196,6 +1201,8 @@ describe('in plugins', () => {
       {
         async loadModule() {
           return {
+            path: '',
+            base: '/root',
             module: plugin(({ addBase, addUtilities }) => {
               addBase({
                 '.my-base-rule': {
@@ -1212,7 +1219,6 @@ describe('in plugins', () => {
                 },
               })
             }),
-            base: '/root',
           }
         },
       },
@@ -1253,6 +1259,8 @@ describe('in JS config files', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: {
             theme: {
               extend: {
@@ -1279,7 +1287,6 @@ describe('in JS config files', () => {
               }),
             ],
           },
-          base: '/root',
         }),
       },
     )
@@ -1314,6 +1321,7 @@ test('replaces CSS theme() function with values inside imported stylesheets', as
       {
         async loadStylesheet() {
           return {
+            path: '',
             base: '/bar.css',
             content: css`
               .red {

packages/tailwindcss/src/css-parser.bench.ts

@@ -10,3 +10,7 @@ const cssFile = readFileSync(currentFolder + './preflight.css', 'utf-8')
 bench('css-parser on preflight.css', () => {
   CSS.parse(cssFile)
 })
+
+bench('CSS with sourcemaps', () => {
+  CSS.parse(cssFile, { from: 'input.css' })
+})

packages/tailwindcss/src/css-parser.test.ts

@@ -86,7 +86,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
           kind: 'comment',
           value: `!
             * License #2
-            `,
+            `.replaceAll(/\r?\n/g, lineEndings === 'Windows' ? '\r\n' : '\n'),
         },
       ])
     })
@@ -368,7 +368,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
               background-color: red;
               /* A comment */
               content: 'Hello, world!';
-            }`,
+            }`.replaceAll(/\r?\n/g, lineEndings === 'Windows' ? '\r\n' : '\n'),
             important: false,
           },
         ])
@@ -396,7 +396,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
               background-color: red;
               /* A comment ; */
               content: 'Hello, world!';
-            }`,
+            }`.replaceAll(/\r?\n/g, lineEndings === 'Windows' ? '\r\n' : '\n'),
             important: false,
           },
           {
@@ -406,7 +406,7 @@ describe.each(['Unix', 'Windows'])('Line endings: %s', (lineEndings) => {
               background-color: red;
               /* A comment } */
               content: 'Hello, world!';
-            }`,
+            }`.replaceAll(/\r?\n/g, lineEndings === 'Windows' ? '\r\n' : '\n'),
             important: false,
           },
         ])

packages/tailwindcss/src/css-parser.ts

@@ -9,6 +9,7 @@ import {
   type Declaration,
   type Rule,
 } from './ast'
+import type { Source } from './source-maps/source'
 
 const BACKSLASH = 0x5c
 const SLASH = 0x2f
@@ -18,6 +19,7 @@ const SINGLE_QUOTE = 0x27
 const COLON = 0x3a
 const SEMICOLON = 0x3b
 const LINE_BREAK = 0x0a
+const CARRIAGE_RETURN = 0xd
 const SPACE = 0x20
 const TAB = 0x09
 const OPEN_CURLY = 0x7b
@@ -30,9 +32,17 @@ const DASH = 0x2d
 const AT_SIGN = 0x40
 const EXCLAMATION_MARK = 0x21
 
-export function parse(input: string) {
-  if (input[0] === '\uFEFF') input = input.slice(1)
-  input = input.replaceAll('\r\n', '\n')
+export interface ParseOptions {
+  from?: string
+}
+
+export function parse(input: string, opts?: ParseOptions) {
+  let source: Source | null = opts?.from ? { file: opts.from, code: input } : null
+
+  // Note: it is important that any transformations of the input string
+  // *before* processing do NOT change the length of the string. This
+  // would invalidate the mechanism used to track source locations.
+  if (input[0] === '\uFEFF') input = ' ' + input.slice(1)
 
   let ast: AstNode[] = []
   let licenseComments: Comment[] = []
@@ -45,11 +55,22 @@ export function parse(input: string) {
   let buffer = ''
   let closingBracketStack = ''
 
+  // The start of the first non-whitespace character in the buffer
+  let bufferStart = 0
+
   let peekChar
 
   for (let i = 0; i < input.length; i++) {
     let currentChar = input.charCodeAt(i)
 
+    // Skip over the CR in CRLF. This allows code below to only check for a line
+    // break even if we're looking at a Windows newline. Peeking the input still
+    // has to check for CRLF but that happens less often.
+    if (currentChar === CARRIAGE_RETURN) {
+      peekChar = input.charCodeAt(i + 1)
+      if (peekChar === LINE_BREAK) continue
+    }
+
     // Current character is a `\` therefore the next character is escaped,
     // consume it together with the next character and continue.
     //
@@ -61,6 +82,7 @@ export function parse(input: string) {
     // ```
     //
     if (currentChar === BACKSLASH) {
+      if (buffer === '') bufferStart = i
       buffer += input.slice(i, i + 2)
       i += 1
     }
@@ -104,7 +126,13 @@ export function parse(input: string) {
       // Collect all license comments so that we can hoist them to the top of
       // the AST.
       if (commentString.charCodeAt(2) === EXCLAMATION_MARK) {
-        licenseComments.push(comment(commentString.slice(2, -2)))
+        let node = comment(commentString.slice(2, -2))
+        licenseComments.push(node)
+
+        if (source) {
+          node.src = [source, start, i + 1]
+          node.dst = [source, start, i + 1]
+        }
       }
     }
 
@@ -146,7 +174,11 @@ export function parse(input: string) {
         //                                    ^ Missing "
         // }
         // ```
-        else if (peekChar === SEMICOLON && input.charCodeAt(j + 1) === LINE_BREAK) {
+        else if (
+          peekChar === SEMICOLON &&
+          (input.charCodeAt(j + 1) === LINE_BREAK ||
+            (input.charCodeAt(j + 1) === CARRIAGE_RETURN && input.charCodeAt(j + 2) === LINE_BREAK))
+        ) {
           throw new Error(
             `Unterminated string: ${input.slice(start, j + 1) + String.fromCharCode(currentChar)}`,
           )
@@ -162,7 +194,10 @@ export function parse(input: string) {
         //                                    ^ Missing "
         // }
         // ```
-        else if (peekChar === LINE_BREAK) {
+        else if (
+          peekChar === LINE_BREAK ||
+          (peekChar === CARRIAGE_RETURN && input.charCodeAt(j + 1) === LINE_BREAK)
+        ) {
           throw new Error(
             `Unterminated string: ${input.slice(start, j) + String.fromCharCode(currentChar)}`,
           )
@@ -178,7 +213,12 @@ export function parse(input: string) {
     else if (
       (currentChar === SPACE || currentChar === LINE_BREAK || currentChar === TAB) &&
       (peekChar = input.charCodeAt(i + 1)) &&
-      (peekChar === SPACE || peekChar === LINE_BREAK || peekChar === TAB)
+      (peekChar === SPACE ||
+        peekChar === LINE_BREAK ||
+        peekChar === TAB ||
+        (peekChar === CARRIAGE_RETURN &&
+          (peekChar = input.charCodeAt(i + 2)) &&
+          peekChar == LINE_BREAK))
     ) {
       continue
     }
@@ -289,6 +329,11 @@ export function parse(input: string) {
       let declaration = parseDeclaration(buffer, colonIdx)
       if (!declaration) throw new Error(`Invalid custom property, expected a value`)
 
+      if (source) {
+        declaration.src = [source, start, i]
+        declaration.dst = [source, start, i]
+      }
+
       if (parent) {
         parent.nodes.push(declaration)
       } else {
@@ -309,6 +354,11 @@ export function parse(input: string) {
     else if (currentChar === SEMICOLON && buffer.charCodeAt(0) === AT_SIGN) {
       node = parseAtRule(buffer)
 
+      if (source) {
+        node.src = [source, bufferStart, i]
+        node.dst = [source, bufferStart, i]
+      }
+
       // At-rule is nested inside of a rule, attach it to the parent.
       if (parent) {
         parent.nodes.push(node)
@@ -345,6 +395,11 @@ export function parse(input: string) {
         throw new Error(`Invalid declaration: \`${buffer.trim()}\``)
       }
 
+      if (source) {
+        declaration.src = [source, bufferStart, i]
+        declaration.dst = [source, bufferStart, i]
+      }
+
       if (parent) {
         parent.nodes.push(declaration)
       } else {
@@ -364,6 +419,12 @@ export function parse(input: string) {
       // At this point `buffer` should resemble a selector or an at-rule.
       node = rule(buffer.trim())
 
+      // Track the source location for source maps
+      if (source) {
+        node.src = [source, bufferStart, i]
+        node.dst = [source, bufferStart, i]
+      }
+
       // Attach the rule to the parent in case it's nested.
       if (parent) {
         parent.nodes.push(node)
@@ -410,6 +471,12 @@ export function parse(input: string) {
         if (buffer.charCodeAt(0) === AT_SIGN) {
           node = parseAtRule(buffer)
 
+          // Track the source location for source maps
+          if (source) {
+            node.src = [source, bufferStart, i]
+            node.dst = [source, bufferStart, i]
+          }
+
           // At-rule is nested inside of a rule, attach it to the parent.
           if (parent) {
             parent.nodes.push(node)
@@ -446,6 +513,11 @@ export function parse(input: string) {
             let node = parseDeclaration(buffer, colonIdx)
             if (!node) throw new Error(`Invalid declaration: \`${buffer.trim()}\``)
 
+            if (source) {
+              node.src = [source, bufferStart, i]
+              node.dst = [source, bufferStart, i]
+            }
+
             parent.nodes.push(node)
           }
         }
@@ -495,6 +567,8 @@ export function parse(input: string) {
         continue
       }
 
+      if (buffer === '') bufferStart = i
+
       buffer += String.fromCharCode(currentChar)
     }
   }
@@ -503,7 +577,15 @@ export function parse(input: string) {
   // means that we have an at-rule that is not terminated with a semicolon at
   // the end of the input.
   if (buffer.charCodeAt(0) === AT_SIGN) {
-    ast.push(parseAtRule(buffer))
+    let node = parseAtRule(buffer)
+
+    // Track the source location for source maps
+    if (source) {
+      node.src = [source, bufferStart, input.length]
+      node.dst = [source, bufferStart, input.length]
+    }
+
+    ast.push(node)
   }
 
   // When we are done parsing then everything should be balanced. If we still
@@ -525,6 +607,9 @@ export function parse(input: string) {
 }
 
 export function parseAtRule(buffer: string, nodes: AstNode[] = []): AtRule {
+  let name = buffer
+  let params = ''
+
   // Assumption: The smallest at-rule in CSS right now is `@page`, this means
   //             that we can always skip the first 5 characters and start at the
   //             sixth (at index 5).
@@ -545,13 +630,13 @@ export function parseAtRule(buffer: string, nodes: AstNode[] = []): AtRule {
   for (let i = 5 /* '@page'.length */; i < buffer.length; i++) {
     let currentChar = buffer.charCodeAt(i)
     if (currentChar === SPACE || currentChar === OPEN_PAREN) {
-      let name = buffer.slice(0, i).trim()
-      let params = buffer.slice(i).trim()
-      return atRule(name, params, nodes)
+      name = buffer.slice(0, i)
+      params = buffer.slice(i)
+      break
     }
   }
 
-  return atRule(buffer.trim(), '', nodes)
+  return atRule(name.trim(), params.trim(), nodes)
 }
 
 function parseDeclaration(

packages/tailwindcss/src/index.test.ts

@@ -126,11 +126,12 @@ describe('compiling CSS', () => {
         {
           async loadStylesheet(id) {
             return {
+              path: '',
+              base: '',
               content: fs.readFileSync(
                 path.resolve(__dirname, '..', id === 'tailwindcss' ? 'index.css' : id),
                 'utf-8',
               ),
-              base: '',
             }
           },
         },
@@ -401,6 +402,7 @@ describe('@apply', () => {
         {
           async loadStylesheet() {
             return {
+              path: '',
               base: '/bar.css',
               content: css`
                 .foo {
@@ -2320,6 +2322,8 @@ describe('Parsing theme values from CSS', () => {
         {
           async loadStylesheet() {
             return {
+              path: '',
+              base: '',
               content: css`
                 @theme {
                   --color-tomato: #e10c04;
@@ -2329,7 +2333,6 @@ describe('Parsing theme values from CSS', () => {
 
                 @tailwind utilities;
               `,
-              base: '',
             }
           },
         },
@@ -2407,6 +2410,8 @@ describe('Parsing theme values from CSS', () => {
         {
           async loadStylesheet() {
             return {
+              path: '',
+              base: '',
               content: css`
                 @theme {
                   --color-tomato: #e10c04;
@@ -2416,7 +2421,6 @@ describe('Parsing theme values from CSS', () => {
 
                 @tailwind utilities;
               `,
-              base: '',
             }
           },
         },
@@ -2704,6 +2708,8 @@ describe('Parsing theme values from CSS', () => {
       {
         loadModule: async () => {
           return {
+            path: '',
+            base: '/root',
             module: plugin(({}) => {}, {
               theme: {
                 extend: {
@@ -2714,7 +2720,6 @@ describe('Parsing theme values from CSS', () => {
                 },
               },
             }),
-            base: '/root',
           }
         },
       },
@@ -2750,6 +2755,8 @@ describe('Parsing theme values from CSS', () => {
       {
         loadModule: async () => {
           return {
+            path: '',
+            base: '/root',
             module: {
               theme: {
                 extend: {
@@ -2760,7 +2767,6 @@ describe('Parsing theme values from CSS', () => {
                 },
               },
             },
-            base: '/root',
           }
         },
       },
@@ -2839,10 +2845,11 @@ describe('plugins', () => {
         `,
         {
           loadModule: async () => ({
+            path: '',
+            base: '/root',
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', '&:hover, &:focus')
             },
-            base: '/root',
           }),
         },
       ),
@@ -2857,10 +2864,11 @@ describe('plugins', () => {
         `,
         {
           loadModule: async () => ({
+            path: '',
+            base: '/root',
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', '&:hover, &:focus')
             },
-            base: '/root',
           }),
         },
       ),
@@ -2877,10 +2885,11 @@ describe('plugins', () => {
         `,
         {
           loadModule: async () => ({
+            path: '',
+            base: '/root',
             module: ({ addVariant }: PluginAPI) => {
               addVariant('hocus', '&:hover, &:focus')
             },
-            base: '/root',
           }),
         },
       ),
@@ -2899,6 +2908,8 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: plugin.withOptions((options) => {
             expect(options).toEqual({
               color: 'red',
@@ -2912,7 +2923,6 @@ describe('plugins', () => {
               })
             }
           }),
-          base: '/root',
         }),
       },
     )
@@ -2951,6 +2961,8 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: plugin.withOptions((options) => {
             expect(options).toEqual({
               'is-null': null,
@@ -2971,7 +2983,6 @@ describe('plugins', () => {
 
             return () => {}
           }),
-          base: '/root',
         }),
       },
     )
@@ -2991,6 +3002,8 @@ describe('plugins', () => {
         `,
         {
           loadModule: async () => ({
+            path: '',
+            base: '/root',
             module: plugin.withOptions((options) => {
               return ({ addUtilities }) => {
                 addUtilities({
@@ -3000,7 +3013,6 @@ describe('plugins', () => {
                 })
               }
             }),
-            base: '/root',
           }),
         },
       ),
@@ -3029,6 +3041,8 @@ describe('plugins', () => {
         `,
         {
           loadModule: async () => ({
+            path: '',
+            base: '/root',
             module: plugin(({ addUtilities }) => {
               addUtilities({
                 '.text-primary': {
@@ -3036,7 +3050,6 @@ describe('plugins', () => {
                 },
               })
             }),
-            base: '/root',
           }),
         },
       ),
@@ -3054,7 +3067,11 @@ describe('plugins', () => {
           }
         `,
         {
-          loadModule: async () => ({ module: plugin(() => {}), base: '/root' }),
+          loadModule: async () => ({
+            path: '',
+            base: '/root',
+            module: plugin(() => {}),
+          }),
         },
       ),
     ).rejects.toThrowErrorMatchingInlineSnapshot(
@@ -3075,7 +3092,11 @@ describe('plugins', () => {
           }
         `,
         {
-          loadModule: async () => ({ module: plugin(() => {}), base: '/root' }),
+          loadModule: async () => ({
+            path: '',
+            base: '/root',
+            module: plugin(() => {}),
+          }),
         },
       ),
     ).rejects.toThrowErrorMatchingInlineSnapshot(`
@@ -3099,10 +3120,11 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: ({ addVariant }: PluginAPI) => {
             addVariant('hocus', '&:hover, &:focus')
           },
-          base: '/root',
         }),
       },
     )
@@ -3131,10 +3153,11 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: ({ addVariant }: PluginAPI) => {
             addVariant('hocus', ['&:hover', '&:focus'])
           },
-          base: '/root',
         }),
       },
     )
@@ -3164,13 +3187,14 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: ({ addVariant }: PluginAPI) => {
             addVariant('hocus', {
               '&:hover': '@slot',
               '&:focus': '@slot',
             })
           },
-          base: '/root',
         }),
       },
     )
@@ -3199,6 +3223,8 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: ({ addVariant }: PluginAPI) => {
             addVariant('hocus', {
               '@media (hover: hover)': {
@@ -3207,7 +3233,6 @@ describe('plugins', () => {
               '&:focus': '@slot',
             })
           },
-          base: '/root',
         }),
       },
     )
@@ -3248,6 +3273,8 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: ({ addVariant }: PluginAPI) => {
             addVariant('hocus', {
               '&': {
@@ -3257,7 +3284,6 @@ describe('plugins', () => {
               },
             })
           },
-          base: '/root',
         }),
       },
     )
@@ -3286,10 +3312,11 @@ describe('plugins', () => {
       `,
       {
         loadModule: async () => ({
+          path: '',
+          base: '/root',
           module: ({ addVariant }: PluginAPI) => {
             addVariant('dark', '&:is([data-theme=dark] *)')
           },
-          base: '/root',
         }),
       },
     )
@@ -4142,6 +4169,8 @@ test('addBase', async () => {
     `,
     {
       loadModule: async () => ({
+        path: '',
+        base: '/root',
         module: ({ addBase }: PluginAPI) => {
           addBase({
             body: {
@@ -4149,7 +4178,6 @@ test('addBase', async () => {
             },
           })
         },
-        base: '/root',
       }),
     },
   )
@@ -4181,6 +4209,7 @@ it("should error when `layer(…)` is used, but it's not the first param", async
       {
         async loadStylesheet() {
           return {
+            path: '',
             base: '/bar.css',
             content: css`
               .foo {
@@ -4201,6 +4230,8 @@ describe('`@reference "…" imports`', () => {
     let loadStylesheet = async (id: string, base: string) => {
       if (id === './foo/baz.css') {
         return {
+          path: '',
+          base: '/root/foo',
           content: css`
             .foo {
               color: red;
@@ -4213,14 +4244,14 @@ describe('`@reference "…" imports`', () => {
             }
             @custom-variant hocus (&:hover, &:focus);
           `,
-          base: '/root/foo',
         }
       }
       return {
+        path: '',
+        base: '/root/foo',
         content: css`
           @import './foo/baz.css';
         `,
-        base: '/root/foo',
       }
     }
 
@@ -4249,19 +4280,21 @@ describe('`@reference "…" imports`', () => {
     let loadStylesheet = async (id: string, base: string) => {
       if (id === './foo/baz.css') {
         return {
+          path: '',
+          base: '/root/foo',
           content: css`
             @layer utilities {
               @tailwind utilities;
             }
           `,
-          base: '/root/foo',
         }
       }
       return {
+        path: '',
+        base: '/root/foo',
         content: css`
           @import './foo/baz.css';
         `,
-        base: '/root/foo',
       }
     }
 
@@ -4311,6 +4344,8 @@ describe('`@reference "…" imports`', () => {
         ['animate-spin', 'match-utility-initial', 'match-components-initial'],
         {
           loadModule: async () => ({
+            path: '',
+            base: '/root',
             module: ({
               addBase,
               addUtilities,
@@ -4344,7 +4379,6 @@ describe('`@reference "…" imports`', () => {
                 { values: { initial: 'initial' } },
               )
             },
-            base: '/root',
           }),
         },
       ),
@@ -4366,22 +4400,26 @@ describe('`@reference "…" imports`', () => {
       switch (id) {
         case './one.css': {
           return {
+            path: '',
+            base: '/root',
             content: css`
               @import './two.css' layer(two);
             `,
-            base: '/root',
           }
         }
         case './two.css': {
           return {
+            path: '',
+            base: '/root',
             content: css`
               @import './three.css' layer(three);
             `,
-            base: '/root',
           }
         }
         case './three.css': {
           return {
+            path: '',
+            base: '/root',
             content: css`
               .foo {
                 color: red;
@@ -4400,10 +4438,11 @@ describe('`@reference "…" imports`', () => {
                 }
               }
             `,
-            base: '/root',
           }
         }
       }
+
+      throw new Error('unreachable')
     }
 
     await expect(
@@ -4438,6 +4477,8 @@ describe('`@reference "…" imports`', () => {
   test('supports `@import "…" reference` syntax', async () => {
     let loadStylesheet = async () => {
       return {
+        path: '',
+        base: '/root/foo',
         content: css`
           .foo {
             color: red;
@@ -4450,7 +4491,6 @@ describe('`@reference "…" imports`', () => {
           }
           @custom-variant hocus (&:hover, &:focus);
         `,
-        base: '/root/foo',
       }
     }
 

packages/tailwindcss/src/index.ts

@@ -26,6 +26,7 @@ import { applyVariant, compileCandidates } from './compile'
 import { substituteFunctions } from './css-functions'
 import * as CSS from './css-parser'
 import { buildDesignSystem, type DesignSystem } from './design-system'
+import { createSourceMap, type DecodedSourceMap } from './source-maps/source-map'
 import { Theme, ThemeOptions } from './theme'
 import { createCssUtility } from './utilities'
 import { expand } from './utils/brace-expansion'
@@ -51,13 +52,25 @@ export const enum Polyfills {
 
 type CompileOptions = {
   base?: string
+  from?: string
   polyfills?: Polyfills
   loadModule?: (
     id: string,
     base: string,
     resourceHint: 'plugin' | 'config',
-  ) => Promise<{ module: Plugin | Config; base: string }>
-  loadStylesheet?: (id: string, base: string) => Promise<{ content: string; base: string }>
+  ) => Promise<{
+    path: string
+    base: string
+    module: Plugin | Config
+  }>
+  loadStylesheet?: (
+    id: string,
+    base: string,
+  ) => Promise<{
+    path: string
+    base: string
+    content: string
+  }>
 }
 
 function throwOnLoadModule(): never {
@@ -125,6 +138,7 @@ async function parseCss(
   ast: AstNode[],
   {
     base = '',
+    from,
     loadModule = throwOnLoadModule,
     loadStylesheet = throwOnLoadStylesheet,
   }: CompileOptions = {},
@@ -132,7 +146,7 @@ async function parseCss(
   let features = Features.None
   ast = [contextNode({ base }, ast)] as AstNode[]
 
-  features |= await substituteAtImports(ast, base, loadStylesheet)
+  features |= await substituteAtImports(ast, base, loadStylesheet, 0, from !== undefined)
 
   let important = null as boolean | null
   let theme = new Theme()
@@ -528,7 +542,7 @@ async function parseCss(
 
         if (child.kind === 'comment') return
         if (child.kind === 'declaration' && child.property.startsWith('--')) {
-          theme.add(unescape(child.property), child.value ?? '', themeOptions)
+          theme.add(unescape(child.property), child.value ?? '', themeOptions, child.src)
           return
         }
 
@@ -546,6 +560,7 @@ async function parseCss(
       // theme later, and delete any other `@theme` rules.
       if (!firstThemeRule) {
         firstThemeRule = styleRule(':root, :host', [])
+        firstThemeRule.src = node.src
         replaceWith([firstThemeRule])
       } else {
         replaceWith([])
@@ -593,8 +608,9 @@ async function parseCss(
 
     for (let [key, value] of designSystem.theme.entries()) {
       if (value.options & ThemeOptions.REFERENCE) continue
-
-      nodes.push(decl(escape(key), value.value))
+      let node = decl(escape(key), value.value)
+      node.src = value.src
+      nodes.push(node)
     }
 
     let keyframesRules = designSystem.theme.getKeyframes()
@@ -748,6 +764,16 @@ export async function compileAst(
         onInvalidCandidate,
       }).astNodes
 
+      if (opts.from) {
+        walk(newNodes, (node) => {
+          // We do this conditionally to preserve source locations from both
+          // `@utility` and `@custom-variant`. Even though generated nodes are
+          // cached this should be fine because `utilitiesNode.src` should not
+          // change without a full rebuild which destroys the cache.
+          node.src ??= utilitiesNode.src
+        })
+      }
+
       // If no new ast nodes were generated, then we can return the original
       // CSS. This currently assumes that we only add new ast nodes and never
       // remove any.
@@ -766,6 +792,8 @@ export async function compileAst(
   }
 }
 
+export type { DecodedSourceMap }
+
 export async function compile(
   css: string,
   opts: CompileOptions = {},
@@ -774,8 +802,9 @@ export async function compile(
   root: Root
   features: Features
   build(candidates: string[]): string
+  buildSourceMap(): DecodedSourceMap
 }> {
-  let ast = CSS.parse(css)
+  let ast = CSS.parse(css, { from: opts.from })
   let api = await compileAst(ast, opts)
   let compiledAst = ast
   let compiledCss = css
@@ -789,11 +818,17 @@ export async function compile(
         return compiledCss
       }
 
-      compiledCss = toCss(newAst)
+      compiledCss = toCss(newAst, !!opts.from)
       compiledAst = newAst
 
       return compiledCss
     },
+
+    buildSourceMap() {
+      return createSourceMap({
+        ast: compiledAst,
+      })
+    },
   }
 }
 

packages/tailwindcss/src/intellisense.test.ts

@@ -172,10 +172,12 @@ test('Utilities do not show wrapping selector in intellisense', async () => {
 
   let design = await __unstable__loadDesignSystem(input, {
     loadStylesheet: async (_, base) => ({
+      path: '',
       base,
       content: '@tailwind utilities;',
     }),
     loadModule: async () => ({
+      path: '',
       base: '',
       module: {
         important: '#app',
@@ -208,6 +210,7 @@ test('Utilities, when marked as important, show as important in intellisense', a
 
   let design = await __unstable__loadDesignSystem(input, {
     loadStylesheet: async (_, base) => ({
+      path: '',
       base,
       content: '@tailwind utilities;',
     }),
@@ -239,10 +242,12 @@ test('Static utilities from plugins are listed in hovers and completions', async
 
   let design = await __unstable__loadDesignSystem(input, {
     loadStylesheet: async (_, base) => ({
+      path: '',
       base,
       content: '@tailwind utilities;',
     }),
     loadModule: async () => ({
+      path: '',
       base: '',
       module: plugin(({ addUtilities }) => {
         addUtilities({
@@ -274,10 +279,12 @@ test('Functional utilities from plugins are listed in hovers and completions', a
 
   let design = await __unstable__loadDesignSystem(input, {
     loadStylesheet: async (_, base) => ({
+      path: '',
       base,
       content: '@tailwind utilities;',
     }),
     loadModule: async () => ({
+      path: '',
       base: '',
       module: plugin(({ matchUtilities }) => {
         matchUtilities(
@@ -420,10 +427,12 @@ test('Custom at-rule variants do not show up as a value under `group`', async ()
 
   let design = await __unstable__loadDesignSystem(input, {
     loadStylesheet: async (_, base) => ({
+      path: '',
       base,
       content: '@tailwind utilities;',
     }),
     loadModule: async () => ({
+      path: '',
       base: '',
       module: plugin(({ addVariant }) => {
         addVariant('variant-3', '@media baz')
@@ -510,6 +519,7 @@ test('Custom functional @utility', async () => {
 
   let design = await __unstable__loadDesignSystem(input, {
     loadStylesheet: async (_, base) => ({
+      path: '',
       base,
       content: '@tailwind utilities;',
     }),
@@ -587,6 +597,7 @@ test('Theme keys with underscores are suggested with underscores', async () => {
 
   let design = await __unstable__loadDesignSystem(input, {
     loadStylesheet: async (_, base) => ({
+      path: '',
       base,
       content: '@tailwind utilities;',
     }),

packages/tailwindcss/src/prefix.test.ts

@@ -169,6 +169,7 @@ test('JS theme functions do not use the prefix', async () => {
     {
       async loadModule(id, base) {
         return {
+          path: '',
           base,
           module: plugin(({ addUtilities, theme }) => {
             addUtilities({
@@ -206,6 +207,7 @@ test('a prefix can be configured via @import theme(…)', async () => {
   let compiler = await compile(input, {
     async loadStylesheet(id, base) {
       return {
+        path: '',
         base,
         content: css`
           @theme {
@@ -250,6 +252,7 @@ test('a prefix can be configured via @import theme(…)', async () => {
   compiler = await compile(input, {
     async loadStylesheet(id, base) {
       return {
+        path: '',
         base,
         content: css`
           @theme {
@@ -275,6 +278,7 @@ test('a prefix can be configured via @import prefix(…)', async () => {
   let compiler = await compile(input, {
     async loadStylesheet(id, base) {
       return {
+        path: '',
         base,
         content: css`
           @theme {
@@ -314,6 +318,7 @@ test('a prefix can be configured via @import prefix(…)', async () => {
   compiler = await compile(input, {
     async loadStylesheet(id, base) {
       return {
+        path: '',
         base,
         content: css`
           @theme {

packages/tailwindcss/src/source-maps/line-table.bench.ts

@@ -0,0 +1,13 @@
+import { readFileSync } from 'node:fs'
+import { fileURLToPath } from 'node:url'
+
+import { bench } from 'vitest'
+import { createLineTable } from './line-table'
+
+const currentFolder = fileURLToPath(new URL('..', import.meta.url))
+const cssFile = readFileSync(currentFolder + '../preflight.css', 'utf-8')
+const table = createLineTable(cssFile)
+
+bench('line table lookups', () => {
+  for (let i = 0; i < cssFile.length; ++i) table.find(i)
+})

packages/tailwindcss/src/source-maps/line-table.test.ts

@@ -0,0 +1,87 @@
+import dedent from 'dedent'
+import { expect, test } from 'vitest'
+import { createLineTable } from './line-table'
+
+const css = dedent
+
+test('line tables', () => {
+  let text = css`
+    .foo {
+      color: red;
+    }
+  `
+
+  let table = createLineTable(`${text}\n`)
+
+  // Line 1: `.foo {\n`
+  expect(table.find(0)).toEqual({ line: 1, column: 0 })
+  expect(table.find(1)).toEqual({ line: 1, column: 1 })
+  expect(table.find(2)).toEqual({ line: 1, column: 2 })
+  expect(table.find(3)).toEqual({ line: 1, column: 3 })
+  expect(table.find(4)).toEqual({ line: 1, column: 4 })
+  expect(table.find(5)).toEqual({ line: 1, column: 5 })
+  expect(table.find(6)).toEqual({ line: 1, column: 6 })
+
+  // Line 2: `  color: red;\n`
+  expect(table.find(6 + 1)).toEqual({ line: 2, column: 0 })
+  expect(table.find(6 + 2)).toEqual({ line: 2, column: 1 })
+  expect(table.find(6 + 3)).toEqual({ line: 2, column: 2 })
+  expect(table.find(6 + 4)).toEqual({ line: 2, column: 3 })
+  expect(table.find(6 + 5)).toEqual({ line: 2, column: 4 })
+  expect(table.find(6 + 6)).toEqual({ line: 2, column: 5 })
+  expect(table.find(6 + 7)).toEqual({ line: 2, column: 6 })
+  expect(table.find(6 + 8)).toEqual({ line: 2, column: 7 })
+  expect(table.find(6 + 9)).toEqual({ line: 2, column: 8 })
+  expect(table.find(6 + 10)).toEqual({ line: 2, column: 9 })
+  expect(table.find(6 + 11)).toEqual({ line: 2, column: 10 })
+  expect(table.find(6 + 12)).toEqual({ line: 2, column: 11 })
+  expect(table.find(6 + 13)).toEqual({ line: 2, column: 12 })
+
+  // Line 3: `}\n`
+  expect(table.find(20 + 1)).toEqual({ line: 3, column: 0 })
+  expect(table.find(20 + 2)).toEqual({ line: 3, column: 1 })
+
+  // After the new line
+  expect(table.find(22 + 1)).toEqual({ line: 4, column: 0 })
+})
+
+test('line tables findOffset', () => {
+  let text = css`
+    .foo {
+      color: red;
+    }
+  `
+
+  let table = createLineTable(`${text}\n`)
+
+  // Line 1: `.foo {\n`
+  expect(table.findOffset({ line: 1, column: 0 })).toEqual(0)
+  expect(table.findOffset({ line: 1, column: 1 })).toEqual(1)
+  expect(table.findOffset({ line: 1, column: 2 })).toEqual(2)
+  expect(table.findOffset({ line: 1, column: 3 })).toEqual(3)
+  expect(table.findOffset({ line: 1, column: 4 })).toEqual(4)
+  expect(table.findOffset({ line: 1, column: 5 })).toEqual(5)
+  expect(table.findOffset({ line: 1, column: 6 })).toEqual(6)
+
+  // Line 2: `  color: red;\n`
+  expect(table.findOffset({ line: 2, column: 0 })).toEqual(6 + 1)
+  expect(table.findOffset({ line: 2, column: 1 })).toEqual(6 + 2)
+  expect(table.findOffset({ line: 2, column: 2 })).toEqual(6 + 3)
+  expect(table.findOffset({ line: 2, column: 3 })).toEqual(6 + 4)
+  expect(table.findOffset({ line: 2, column: 4 })).toEqual(6 + 5)
+  expect(table.findOffset({ line: 2, column: 5 })).toEqual(6 + 6)
+  expect(table.findOffset({ line: 2, column: 6 })).toEqual(6 + 7)
+  expect(table.findOffset({ line: 2, column: 7 })).toEqual(6 + 8)
+  expect(table.findOffset({ line: 2, column: 8 })).toEqual(6 + 9)
+  expect(table.findOffset({ line: 2, column: 9 })).toEqual(6 + 10)
+  expect(table.findOffset({ line: 2, column: 10 })).toEqual(6 + 11)
+  expect(table.findOffset({ line: 2, column: 11 })).toEqual(6 + 12)
+  expect(table.findOffset({ line: 2, column: 12 })).toEqual(6 + 13)
+
+  // Line 3: `}\n`
+  expect(table.findOffset({ line: 3, column: 0 })).toEqual(20 + 1)
+  expect(table.findOffset({ line: 3, column: 1 })).toEqual(20 + 2)
+
+  // After the new line
+  expect(table.findOffset({ line: 4, column: 0 })).toEqual(22 + 1)
+})

packages/tailwindcss/src/source-maps/line-table.ts

@@ -0,0 +1,100 @@
+/**
+ * Line offset tables are the key to generating our source maps. They allow us
+ * to store indexes with our AST nodes and later convert them into positions as
+ * when given the source that the indexes refer to.
+ */
+
+const LINE_BREAK = 0x0a
+
+/**
+ * A position in source code
+ *
+ * https://tc39.es/ecma426/#sec-position-record-type
+ */
+export interface Position {
+  /** The line number, one-based */
+  line: number
+
+  /** The column/character number, one-based */
+  column: number
+}
+
+/**
+ * A table that lets you turn an offset into a line number and column
+ */
+export interface LineTable {
+  /**
+   * Find the line/column position in the source code for a given offset
+   *
+   * Searching for a given offset takes O(log N) time where N is the number of
+   * lines of code.
+   *
+   * @param offset The index for which to find the position
+   */
+  find(offset: number): Position
+
+  /**
+   * Find the most likely byte offset for given a position
+   *
+   * @param offset The position for which to find the byte offset
+   */
+  findOffset(pos: Position): number
+}
+
+/**
+ * Compute a lookup table to allow for efficient line/column lookups based on
+ * offsets in the source code.
+ *
+ * Creating this table is an O(N) operation where N is the length of the source
+ */
+export function createLineTable(source: string): LineTable {
+  let table: number[] = [0]
+
+  // Compute the offsets for the start of each line
+  for (let i = 0; i < source.length; i++) {
+    if (source.charCodeAt(i) === LINE_BREAK) {
+      table.push(i + 1)
+    }
+  }
+
+  function find(offset: number) {
+    // Based on esbuild's binary search for line numbers
+    let line = 0
+    let count = table.length
+    while (count > 0) {
+      // `| 0` improves performance (in V8 at least)
+      let mid = (count | 0) >> 1
+      let i = line + mid
+      if (table[i] <= offset) {
+        line = i + 1
+        count = count - mid - 1
+      } else {
+        count = mid
+      }
+    }
+
+    line -= 1
+
+    let column = offset - table[line]
+
+    return {
+      line: line + 1,
+      column: column,
+    }
+  }
+
+  function findOffset({ line, column }: Position) {
+    line -= 1
+    line = Math.min(Math.max(line, 0), table.length - 1)
+
+    let offsetA = table[line]
+    let offsetB = table[line + 1] ?? offsetA
+
+    return Math.min(Math.max(offsetA + column, 0), offsetB)
+  }
+
+  return {
+    find,
+    findOffset,
+  }
+}

packages/tailwindcss/src/source-maps/source-map.ts

@@ -0,0 +1,206 @@
+import { walk, type AstNode } from '../ast'
+import { DefaultMap } from '../utils/default-map'
+import { createLineTable, type LineTable, type Position } from './line-table'
+import type { Source } from './source'
+
+// https://tc39.es/ecma426/#sec-original-position-record-type
+export interface OriginalPosition extends Position {
+  source: DecodedSource
+}
+
+/**
+ * A "decoded" sourcemap
+ *
+ * @see https://tc39.es/ecma426/#decoded-source-map-record
+ */
+export interface DecodedSourceMap {
+  file: string | null
+  sources: DecodedSource[]
+  mappings: DecodedMapping[]
+}
+
+/**
+ * A "decoded" source
+ *
+ * @see https://tc39.es/ecma426/#decoded-source-record
+ */
+export interface DecodedSource {
+  url: string | null
+  content: string | null
+  ignore: boolean
+}
+
+/**
+ * A "decoded" mapping
+ *
+ * @see https://tc39.es/ecma426/#decoded-mapping-record
+ */
+export interface DecodedMapping {
+  // https://tc39.es/ecma426/#sec-original-position-record-type
+  originalPosition: OriginalPosition | null
+
+  // https://tc39.es/ecma426/#sec-position-record-type
+  generatedPosition: Position
+
+  name: string | null
+}
+
+/**
+ * Build a source map from the given AST.
+ *
+ * Our AST is build from flat CSS strings but there are many because we handle
+ * `@import`. This means that different nodes can have a different source.
+ *
+ * Instead of taking an input source map, we take the input CSS string we were
+ * originally given, as well as the source text for any imported files, and
+ * use that to generate a source map.
+ *
+ * We then require the use of other tools that can translate one or more
+ * "input" source maps into a final output source map. For example,
+ * `@ampproject/remapping` can be used to handle this.
+ *
+ * This also ensures that tools that expect "local" source maps are able to
+ * consume the source map we generate.
+ *
+ * The source map type we generate may be a bit different from "raw" source maps
+ * that the `source-map-js` package uses. It's a "decoded" source map that is
+ * represented by an object graph. It's identical to "decoded" source map from
+ * the ECMA-426 spec for source maps.
+ *
+ * Note that the spec itself is still evolving which means our implementation
+ * may need to evolve to match it.
+ *
+ * This can easily be converted to a "raw" source map by any tool that needs to.
+ **/
+export function createSourceMap({ ast }: { ast: AstNode[] }) {
+  // Compute line tables for both the original and generated source lazily so we
+  // don't have to do it during parsing or printing.
+  let lineTables = new DefaultMap<Source, LineTable>((src) => createLineTable(src.code))
+  let sourceTable = new DefaultMap<Source, DecodedSource>((src) => ({
+    url: src.file,
+    content: src.code,
+    ignore: false,
+  }))
+
+  // Convert each mapping to a set of positions
+  let map: DecodedSourceMap = {
+    file: null,
+    sources: [],
+    mappings: [],
+  }
+
+  // Get all the indexes from the mappings
+  walk(ast, (node: AstNode) => {
+    if (!node.src || !node.dst) return
+
+    let originalSource = sourceTable.get(node.src[0])
+    if (!originalSource.content) return
+
+    let originalTable = lineTables.get(node.src[0])
+    let generatedTable = lineTables.get(node.dst[0])
+
+    let originalSlice = originalSource.content.slice(node.src[1], node.src[2])
+
+    // Source maps only encode single locations — not multi-line ranges
+    // So to properly emulate this we'll scan the original text for multiple
+    // lines and create mappings for each of those lines that point to the
+    // destination node (whether it spans multiple lines or not)
+    //
+    // This is not 100% accurate if both the source and destination preserve
+    // their newlines but this only happens in the case of custom properties
+    //
+    // This is _good enough_
+    let offset = 0
+    for (let line of originalSlice.split('\n')) {
+      if (line.trim() !== '') {
+        let originalStart = originalTable.find(node.src[1] + offset)
+        let generatedStart = generatedTable.find(node.dst[1])
+
+        map.mappings.push({
+          name: null,
+          originalPosition: {
+            source: originalSource,
+            ...originalStart,
+          },
+          generatedPosition: generatedStart,
+        })
+      }
+
+      offset += line.length
+      offset += 1
+    }
+
+    let originalEnd = originalTable.find(node.src[2])
+    let generatedEnd = generatedTable.find(node.dst[2])
+
+    map.mappings.push({
+      name: null,
+      originalPosition: {
+        source: originalSource,
+        ...originalEnd,
+      },
+      generatedPosition: generatedEnd,
+    })
+  })
+
+  // Populate
+  for (let source of lineTables.keys()) {
+    map.sources.push(sourceTable.get(source))
+  }
+
+  // Sort the mappings in ascending order
+  map.mappings.sort((a, b) => {
+    let aOriginal = a.originalPosition!
+    let aGenerated = a.generatedPosition!
+    let bOriginal = b.originalPosition!
+    let bGenerated = b.generatedPosition!
+
+    let aSource = map.sources.indexOf(aOriginal.source)
+    let bSource = map.sources.indexOf(bOriginal.source)
+
+    return (
+      aGenerated.line - bGenerated.line ||
+      aGenerated.column - bGenerated.column ||
+      aSource - bSource ||
+      aOriginal.line - bOriginal.line ||
+      aOriginal.column - bGenerated.column
+    )
+  })
+
+  return map
+}
+
+export function createTranslationMap({
+  original,
+  generated,
+}: {
+  original: string
+  generated: string
+}) {
+  // Compute line tables for both the original and generated source lazily so we
+  // don't have to do it during parsing or printing.
+  let originalTable = createLineTable(original)
+  let generatedTable = createLineTable(generated)
+
+  type Translation = [
+    originalStart: Position,
+    originalEnd: Position,
+    generatedStart: Position | null,
+    generatedEnd: Position | null,
+  ]
+
+  return (node: AstNode) => {
+    if (!node.src) return []
+
+    let translations: Translation[] = []
+
+    translations.push([
+      originalTable.find(node.src[1]),
+      originalTable.find(node.src[2]),
+      node.dst ? generatedTable.find(node.dst[1]) : null,
+      node.dst ? generatedTable.find(node.dst[2]) : null,
+    ])
+
+    return translations
+  }
+}

packages/tailwindcss/src/source-maps/source.ts

@@ -0,0 +1,27 @@
+/**
+ * The source code for one or more nodes in the AST
+ *
+ * This generally corresponds to a stylesheet
+ */
+export interface Source {
+  /**
+   * The path to the file that contains the referenced source code
+   *
+   * If this references the *output* source code, this is `null`.
+   */
+  file: string | null
+
+  /**
+   * The referenced source code
+   */
+  code: string
+}
+
+/**
+ * The file and offsets within it that this node covers
+ *
+ * This can represent either:
+ * - A location in the original CSS which caused this node to be created
+ * - A location in the output CSS where this node resides
+ */
+export type SourceLocation = [source: Source, start: number, end: number]

packages/tailwindcss/src/source-maps/visualizer.ts

@@ -0,0 +1,120 @@
+import { DefaultMap } from '../utils/default-map'
+import type { DecodedMapping, DecodedSource, DecodedSourceMap } from './source-map'
+
+interface RangeMapping {
+  id: number
+  source: DecodedSource
+  line: number
+  start: number
+  end: number | null
+}
+
+export function visualize(generated: string, map: DecodedSourceMap) {
+  let outputSource: DecodedSource = {
+    url: 'output.css',
+    content: generated,
+    ignore: false,
+  }
+
+  // Group mappings by source file
+  let bySource = new DefaultMap<DecodedSource, DefaultMap<number, DecodedMapping[]>>(
+    () => new DefaultMap<number, DecodedMapping[]>(() => []),
+  )
+
+  let mappingIds = new Map<DecodedMapping, number>()
+
+  let nextId = 1
+  for (let mapping of map.mappings) {
+    let pos = mapping.originalPosition
+    if (!pos) continue
+    let source = pos.source
+    if (!source) continue
+    bySource.get(source).get(pos.line).push(mapping)
+    mappingIds.set(mapping, nextId++)
+  }
+
+  for (let mapping of map.mappings) {
+    let pos = mapping.generatedPosition
+    if (!pos) continue
+    bySource.get(outputSource).get(pos.line).push(mapping)
+  }
+
+  let maxIdSize = Math.ceil(Math.log10(Math.max(...mappingIds.values())))
+  // `#number  `
+  let gutterSize = 3 + maxIdSize
+
+  let output = ''
+  output += '\n'
+  output += 'SOURCES\n'
+
+  for (let source of bySource.keys()) {
+    if (source === outputSource) continue
+    output += '- '
+    output += source.url ?? 'unknown'
+    output += '\n'
+  }
+
+  output += '\n'
+  output += 'VISUALIZATION\n'
+
+  for (let [source, byLine] of bySource) {
+    if (!source.content) continue
+
+    output += ' '.repeat(gutterSize)
+    output += `/* `
+    if (source === outputSource) {
+      output += `output`
+    } else {
+      output += `input: `
+      output += source.url ?? 'unknown'
+    }
+    output += ` */\n`
+
+    let lines = source.content.split('\n').entries()
+    for (let [lineNum, line] of lines) {
+      output += ' '.repeat(gutterSize)
+      output += line
+      output += '\n'
+
+      let pairs: DecodedMapping[][] = []
+
+      // Get all mappings for this line
+      let lineMappings = byLine.get(lineNum + 1)
+
+      // Group consecutive mappings into pairs
+      for (let i = 0; i < lineMappings.length; i += 2) {
+        let pair = [lineMappings[i]]
+        if (i + 1 < lineMappings.length) {
+          pair.push(lineMappings[i + 1])
+        }
+
+        pairs.push(pair)
+      }
+
+      for (let [start, end] of pairs) {
+        let id = mappingIds.get(start)
+        if (!id) continue
+
+        let startPos = source === outputSource ? start.generatedPosition : start.originalPosition
+        if (!startPos) continue
+
+        let endPos = source === outputSource ? end?.generatedPosition : end?.originalPosition
+
+        output += '#'
+        output += `${Math.floor((id + 1) / 2)}`.padEnd(maxIdSize, ' ')
+        output += '  '
+        output += ' '.repeat(startPos.column)
+
+        if (endPos) {
+          output += '-'.repeat(Math.max(0, endPos.column - startPos.column))
+        } else {
+          output += '^'
+        }
+
+        output += '\n'
+      }
+    }
+  }
+
+  return output
+}

packages/tailwindcss/src/test-utils/run.ts

@@ -7,12 +7,14 @@ export async function compileCss(
   options: Parameters<typeof compile>[1] = {},
 ) {
   let { build } = await compile(css, options)
-  return optimize(build(candidates)).trim()
+  return optimize(build(candidates)).code.trim()
 }
 
 export async function run(candidates: string[]) {
   let { build } = await compile('@tailwind utilities;')
-  return optimize(build(candidates)).trim()
+  return optimize(build(candidates)).code.trim()
 }
 
-export const optimizeCss = optimize
+export function optimizeCss(input: string) {
+  return optimize(input).code
+}

packages/tailwindcss/src/theme.ts

@@ -1,4 +1,4 @@
-import { type AtRule } from './ast'
+import { type AtRule, type Declaration } from './ast'
 import { escape, unescape } from './utils/escape'
 
 export const enum ThemeOptions {
@@ -40,11 +40,18 @@ export class Theme {
   public prefix: string | null = null
 
   constructor(
-    private values = new Map<string, { value: string; options: ThemeOptions }>(),
+    private values = new Map<
+      string,
+      {
+        value: string
+        options: ThemeOptions
+        src: Declaration['src']
+      }
+    >(),
     private keyframes = new Set<AtRule>([]),
   ) {}
 
-  add(key: string, value: string, options = ThemeOptions.NONE): void {
+  add(key: string, value: string, options = ThemeOptions.NONE, src?: Declaration['src']): void {
     if (key.endsWith('-*')) {
       if (value !== 'initial') {
         throw new Error(`Invalid theme value \`${value}\` for namespace \`${key}\``)
@@ -68,7 +75,7 @@ export class Theme {
     if (value === 'initial') {
       this.values.delete(key)
     } else {
-      this.values.set(key, { value, options })
+      this.values.set(key, { value, options, src })
     }
   }
 

packages/tailwindcss/src/variants.test.ts

@@ -2526,8 +2526,9 @@ test('matchVariant sorts deterministically', async () => {
 
   for (let classList of classLists) {
     let output = await compileCss('@tailwind utilities; @plugin "./plugin.js";', classList, {
-      loadModule(id: string) {
+      async loadModule(id: string) {
         return {
+          path: '',
           base: '/',
           module: createPlugin(({ matchVariant }) => {
             matchVariant('is-data', (value) => `&:is([data-${value}])`, {

packages/tailwindcss/tests/ui.spec.ts

@@ -2216,7 +2216,7 @@ async function render(page: Page, content: string, extraCss: string = '') {
   let scanner = new Scanner({})
   let candidates = scanner.scanFiles([{ content, extension: 'html' }])
 
-  let styles = optimize(build(candidates))
+  let { code: styles } = optimize(build(candidates))
 
   content = `<style type="text/css">${styles}</style>${content}`
   await page.setContent(content)

pnpm-lock.yaml

@@ -188,6 +188,9 @@ importers:
       fast-glob:
         specifier: ^3.3.3
         version: 3.3.3
+      source-map-js:
+        specifier: ^1.2.1
+        version: 1.2.1
 
   packages/@tailwindcss-browser:
     devDependencies:
@@ -227,6 +230,9 @@ importers:
 
   packages/@tailwindcss-node:
     dependencies:
+      '@ampproject/remapping':
+        specifier: ^2.3.0
+        version: 2.3.0
       enhanced-resolve:
         specifier: ^5.18.1
         version: 5.18.1
@@ -236,6 +242,12 @@ importers:
       lightningcss:
         specifier: 'catalog:'
         version: 1.29.2(patch_hash=tzyxy3asfxcqc7ihrooumyi5fm)
+      magic-string:
+        specifier: ^0.30.17
+        version: 0.30.17
+      source-map-js:
+        specifier: ^1.2.1
+        version: 1.2.1
       tailwindcss:
         specifier: workspace:*
         version: link:../tailwindcss
@@ -437,6 +449,9 @@ importers:
 
   packages/tailwindcss:
     devDependencies:
+      '@ampproject/remapping':
+        specifier: ^2.3.0
+        version: 2.3.0
       '@tailwindcss/oxide':
         specifier: workspace:^
         version: link:../../crates/node
@@ -449,6 +464,12 @@ importers:
       lightningcss:
         specifier: 'catalog:'
         version: 1.29.2(patch_hash=tzyxy3asfxcqc7ihrooumyi5fm)
+      magic-string:
+        specifier: ^0.30.17
+        version: 0.30.17
+      source-map-js:
+        specifier: ^1.2.1
+        version: 1.2.1
 
   playgrounds/nextjs:
     dependencies:
@@ -2068,7 +2089,6 @@ packages:
   '@parcel/watcher-darwin-arm64@2.5.1':
     resolution: {integrity: sha512-eAzPv5osDmZyBhou8PoF4i6RQXAfeKL9tjb3QzYuccXFMQU0ruIc/POh30ePnaOyD1UXdlKguHBmsTs53tVoPw==}
     engines: {node: '>= 10.0.0'}
-    cpu: [arm64]
     os: [darwin]
 
   '@parcel/watcher-darwin-x64@2.5.0':
@@ -2080,7 +2100,6 @@ packages:
   '@parcel/watcher-darwin-x64@2.5.1':
     resolution: {integrity: sha512-1ZXDthrnNmwv10A0/3AJNZ9JGlzrF82i3gNQcWOzd7nJ8aj+ILyW1MTxVk35Db0u91oD5Nlk9MBiujMlwmeXZg==}
     engines: {node: '>= 10.0.0'}
-    cpu: [x64]
     os: [darwin]
 
   '@parcel/watcher-freebsd-x64@2.5.0':
@@ -2128,7 +2147,6 @@ packages:
   '@parcel/watcher-linux-arm64-glibc@2.5.1':
     resolution: {integrity: sha512-LrGp+f02yU3BN9A+DGuY3v3bmnFUggAITBGriZHUREfNEzZh/GO06FF5u2kx8x+GBEUYfyTGamol4j3m9ANe8w==}
     engines: {node: '>= 10.0.0'}
-    cpu: [arm64]
     os: [linux]
 
   '@parcel/watcher-linux-arm64-musl@2.5.0':
@@ -2140,7 +2158,6 @@ packages:
   '@parcel/watcher-linux-arm64-musl@2.5.1':
     resolution: {integrity: sha512-cFOjABi92pMYRXS7AcQv9/M1YuKRw8SZniCDw0ssQb/noPkRzA+HBDkwmyOJYp5wXcsTrhxO0zq1U11cK9jsFg==}
     engines: {node: '>= 10.0.0'}
-    cpu: [arm64]
     os: [linux]
 
   '@parcel/watcher-linux-x64-glibc@2.5.0':
@@ -2152,7 +2169,6 @@ packages:
   '@parcel/watcher-linux-x64-glibc@2.5.1':
     resolution: {integrity: sha512-GcESn8NZySmfwlTsIur+49yDqSny2IhPeZfXunQi48DMugKeZ7uy1FX83pO0X22sHntJ4Ub+9k34XQCX+oHt2A==}
     engines: {node: '>= 10.0.0'}
-    cpu: [x64]
     os: [linux]
 
   '@parcel/watcher-linux-x64-musl@2.5.0':
@@ -2164,7 +2180,6 @@ packages:
   '@parcel/watcher-linux-x64-musl@2.5.1':
     resolution: {integrity: sha512-n0E2EQbatQ3bXhcH2D1XIAANAcTZkQICBPVaxMeaCVBtOpBZpWJuf7LwyWPSBDITb7In8mqQgJ7gH8CILCURXg==}
     engines: {node: '>= 10.0.0'}
-    cpu: [x64]
     os: [linux]
 
   '@parcel/watcher-wasm@2.5.0':
@@ -2206,7 +2221,6 @@ packages:
   '@parcel/watcher-win32-x64@2.5.1':
     resolution: {integrity: sha512-9lHBdJITeNR++EvSQVUcaZoWupyHfXe1jZvGZ06O/5MflPcuPLtEphScIBL+AiCWBO46tDSHzWyD0uDmmZqsgA==}
     engines: {node: '>= 10.0.0'}
-    cpu: [x64]
     os: [win32]
 
   '@parcel/watcher@2.5.0':
@@ -2621,7 +2635,6 @@ packages:
 
   bun@1.2.11:
     resolution: {integrity: sha512-9brVfsp6/TYVsE3lCl1MUxoyKhvljqyL1MNPErgwsOaS9g4Gzi2nY+W5WtRAXGzLrgz5jzsoGHHwyH/rTeRCIg==}
-    cpu: [arm64, x64, aarch64]
     os: [darwin, linux, win32]
     hasBin: true
 
@@ -3480,13 +3493,11 @@ packages:
   lightningcss-darwin-arm64@1.29.2:
     resolution: {integrity: sha512-cK/eMabSViKn/PG8U/a7aCorpeKLMlK0bQeNHmdb7qUnBkNPnL+oV5DjJUo0kqWsJUapZsM4jCfYItbqBDvlcA==}
     engines: {node: '>= 12.0.0'}
-    cpu: [arm64]
     os: [darwin]
 
   lightningcss-darwin-x64@1.29.2:
     resolution: {integrity: sha512-j5qYxamyQw4kDXX5hnnCKMf3mLlHvG44f24Qyi2965/Ycz829MYqjrVg2H8BidybHBp9kom4D7DR5VqCKDXS0w==}
     engines: {node: '>= 12.0.0'}
-    cpu: [x64]
     os: [darwin]
 
   lightningcss-freebsd-x64@1.29.2:
@@ -3504,25 +3515,21 @@ packages:
   lightningcss-linux-arm64-gnu@1.29.2:
     resolution: {integrity: sha512-KKCpOlmhdjvUTX/mBuaKemp0oeDIBBLFiU5Fnqxh1/DZ4JPZi4evEH7TKoSBFOSOV3J7iEmmBaw/8dpiUvRKlQ==}
     engines: {node: '>= 12.0.0'}
-    cpu: [arm64]
     os: [linux]
 
   lightningcss-linux-arm64-musl@1.29.2:
     resolution: {integrity: sha512-Q64eM1bPlOOUgxFmoPUefqzY1yV3ctFPE6d/Vt7WzLW4rKTv7MyYNky+FWxRpLkNASTnKQUaiMJ87zNODIrrKQ==}
     engines: {node: '>= 12.0.0'}
-    cpu: [arm64]
     os: [linux]
 
   lightningcss-linux-x64-gnu@1.29.2:
     resolution: {integrity: sha512-0v6idDCPG6epLXtBH/RPkHvYx74CVziHo6TMYga8O2EiQApnUPZsbR9nFNrg2cgBzk1AYqEd95TlrsL7nYABQg==}
     engines: {node: '>= 12.0.0'}
-    cpu: [x64]
     os: [linux]
 
   lightningcss-linux-x64-musl@1.29.2:
     resolution: {integrity: sha512-rMpz2yawkgGT8RULc5S4WiZopVMOFWjiItBT7aSfDX4NQav6M44rhn5hjtkKzB+wMTRlLLqxkeYEtQ3dd9696w==}
     engines: {node: '>= 12.0.0'}
-    cpu: [x64]
     os: [linux]
 
   lightningcss-win32-arm64-msvc@1.29.2:
@@ -3534,7 +3541,6 @@ packages:
   lightningcss-win32-x64-msvc@1.29.2:
     resolution: {integrity: sha512-EdIUW3B2vLuHmv7urfzMI/h2fmlnOQBk1xlsDxkN1tCWKjNFjfLhGxYk8C8mzpSfr+A6jFFIi8fU6LbQGsRWjA==}
     engines: {node: '>= 12.0.0'}
-    cpu: [x64]
     os: [win32]
 
   lightningcss@1.29.2:
@@ -3592,8 +3598,8 @@ packages:
   lru-cache@5.1.1:
     resolution: {integrity: sha512-KpNARQA3Iwv+jTA0utUVVbrh+Jlrr1Fv0e56GGzAFOXN7dk/FviaDW8LHmK52DlcH4WP2n6gI8vN1aesBFgo9w==}
 
-  magic-string@0.30.11:
-    resolution: {integrity: sha512-+Wri9p0QHMy+545hKww7YAu5NyzF8iomPL/RQazugQ9+Ez4Ic3mERMd8ZTX5rfK944j+560ZJi8iAwgak1Ac7A==}
+  magic-string@0.30.17:
+    resolution: {integrity: sha512-sNPKHvyjVf7gyjwS4xGTaW/mCnF8wnjtifKBEhxfZ7E/S8tQ0rssrwGNn6q8JH/ohItJfSQp9mBtQYuTlH5QnA==}
 
   merge-stream@2.0.0:
     resolution: {integrity: sha512-abv/qOcuPfk3URPfDzmZU1LKmuw8kT+0nIHvKrKgFrwifol/doWcdA4ZqsWQ8ENrFKkd67Mfpo/LovbIUsbt3w==}
@@ -4113,10 +4119,6 @@ packages:
     resolution: {integrity: sha512-ZA6oR3T/pEyuqwMgAKT0/hAv8oAXckzbkmR0UkUosQ+Mc4RxGoJkRmwHgHufaenlyAgE1Mxgpdcrf75y6XcnDg==}
     engines: {node: '>=14.16'}
 
-  source-map-js@1.2.0:
-    resolution: {integrity: sha512-itJW8lvSA0TXEphiRoawsCksnlf8SyvmFzIhltqAHluXd88pkCd+cXJVHTDwdCr0IzwptSm035IHQktUu1QUMg==}
-    engines: {node: '>=0.10.0'}
-
   source-map-js@1.2.1:
     resolution: {integrity: sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==}
     engines: {node: '>=0.10.0'}
@@ -6156,7 +6158,7 @@ snapshots:
   '@vitest/snapshot@2.0.5':
     dependencies:
       '@vitest/pretty-format': 2.0.5
-      magic-string: 0.30.11
+      magic-string: 0.30.17
       pathe: 1.1.2
 
   '@vitest/spy@2.0.5':
@@ -6817,7 +6819,7 @@ snapshots:
       debug: 4.4.0
       enhanced-resolve: 5.18.1
       eslint: 9.25.1(jiti@2.4.2)
-      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3)(eslint@9.25.1(jiti@2.4.2))
+      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-plugin-import@2.31.0)(eslint@9.25.1(jiti@2.4.2)))(eslint@9.25.1(jiti@2.4.2))
       fast-glob: 3.3.3
       get-tsconfig: 4.8.1
       is-bun-module: 1.2.1
@@ -6836,7 +6838,7 @@ snapshots:
       debug: 4.4.0
       enhanced-resolve: 5.18.1
       eslint: 9.25.1(jiti@2.4.2)
-      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3)(eslint@9.25.1(jiti@2.4.2))
+      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-plugin-import@2.31.0)(eslint@9.25.1(jiti@2.4.2)))(eslint@9.25.1(jiti@2.4.2))
       fast-glob: 3.3.3
       get-tsconfig: 4.8.1
       is-bun-module: 1.2.1
@@ -6849,7 +6851,7 @@ snapshots:
       - eslint-import-resolver-webpack
       - supports-color
 
-  eslint-module-utils@2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3)(eslint@9.25.1(jiti@2.4.2)):
+  eslint-module-utils@2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-plugin-import@2.31.0)(eslint@9.25.1(jiti@2.4.2)))(eslint@9.25.1(jiti@2.4.2)):
     dependencies:
       debug: 3.2.7
     optionalDependencies:
@@ -6860,7 +6862,7 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
-  eslint-module-utils@2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3)(eslint@9.25.1(jiti@2.4.2)):
+  eslint-module-utils@2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-plugin-import@2.31.0)(eslint@9.25.1(jiti@2.4.2)))(eslint@9.25.1(jiti@2.4.2)):
     dependencies:
       debug: 3.2.7
     optionalDependencies:
@@ -6882,7 +6884,7 @@ snapshots:
       doctrine: 2.1.0
       eslint: 9.25.1(jiti@2.4.2)
       eslint-import-resolver-node: 0.3.9
-      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3)(eslint@9.25.1(jiti@2.4.2))
+      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.5.4))(eslint-import-resolver-node@0.3.9)(eslint-plugin-import@2.31.0)(eslint@9.25.1(jiti@2.4.2)))(eslint@9.25.1(jiti@2.4.2))
       hasown: 2.0.2
       is-core-module: 2.15.1
       is-glob: 4.0.3
@@ -6911,7 +6913,7 @@ snapshots:
       doctrine: 2.1.0
       eslint: 9.25.1(jiti@2.4.2)
       eslint-import-resolver-node: 0.3.9
-      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3)(eslint@9.25.1(jiti@2.4.2))
+      eslint-module-utils: 2.12.0(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.6.3(@typescript-eslint/parser@8.11.0(eslint@9.25.1(jiti@2.4.2))(typescript@5.6.3))(eslint-import-resolver-node@0.3.9)(eslint-plugin-import@2.31.0)(eslint@9.25.1(jiti@2.4.2)))(eslint@9.25.1(jiti@2.4.2))
       hasown: 2.0.2
       is-core-module: 2.15.1
       is-glob: 4.0.3
@@ -7560,7 +7562,7 @@ snapshots:
     dependencies:
       yallist: 3.1.1
 
-  magic-string@0.30.11:
+  magic-string@0.30.17:
     dependencies:
       '@jridgewell/sourcemap-codec': 1.5.0
 
@@ -7865,7 +7867,7 @@ snapshots:
     dependencies:
       nanoid: 3.3.7
       picocolors: 1.1.1
-      source-map-js: 1.2.0
+      source-map-js: 1.2.1
 
   postcss@8.4.47:
     dependencies:
@@ -8087,8 +8089,6 @@ snapshots:
 
   slash@5.1.0: {}
 
-  source-map-js@1.2.0: {}
-
   source-map-js@1.2.1: {}
 
   source-map-support@0.5.21:
@@ -8523,7 +8523,7 @@ snapshots:
       chai: 5.1.1
       debug: 4.3.6
       execa: 8.0.1
-      magic-string: 0.30.11
+      magic-string: 0.30.17
       pathe: 1.1.2
       std-env: 3.7.0
       tinybench: 2.9.0