Track theme variables

packages/tailwindcss/src/index.ts

@@ -541,7 +541,7 @@ 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
         }
 
@@ -559,6 +559,7 @@ 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([])
@@ -607,6 +608,7 @@ async function parseCss(
     for (let [key, value] of designSystem.theme.entries()) {
       if (value.options & ThemeOptions.REFERENCE) continue
       let node = decl(escape(key), value.value)
+      node.src = value.src
       nodes.push(node)
     }
 

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 })
     }
   }