This PR adds CSS codemods for migrating existing `@tailwind` directives
to the new alternatives.
This PR has the ability to migrate the following cases:
---
Typical default usage of `@tailwind` directives in v3.
Input:
```css
@tailwind base;
@tailwind components;
@tailwind utilities;
```
Output:
```css
@import 'tailwindcss';
```
---
Similar as above, but always using `@import` instead of `@import`
directly.
Input:
```css
@import 'tailwindcss/base';
@import 'tailwindcss/components';
@import 'tailwindcss/utilities';
```
Output:
```css
@import 'tailwindcss';
```
---
When you are _only_ using `@tailwind base`:
Input:
```css
@tailwind base;
```
Output:
```css
@import 'tailwindcss/theme' layer(theme);
@import 'tailwindcss/preflight' layer(base);
```
---
When you are _only_ using `@tailwind utilities`:
Input:
```css
@tailwind utilities;
```
Output:
```css
@import 'tailwindcss/utilities' layer(utilities);
```
---
If the default order changes (aka, `@tailwind utilities` was defined
_before_ `@tailwind base`), then an additional `@layer` will be added to
the top to re-define the default order.
Input:
```css
@tailwind utilities;
@tailwind base;
```
Output:
```css
@layer theme, components, utilities, base;
@import 'tailwindcss';
```
---
When you are _only_ using `@tailwind base; @tailwind utilities;`:
Input:
```css
@tailwind base;
@tailwind utilities;
```
Output:
```css
@import 'tailwindcss';
```
We currently don't have a concept of `@tailwind components` in v4, so if
you are not using `@tailwind components`, we can expand to the default
`@import 'tailwindcss';` instead of the individual imports.
---
`@tailwind screens` and `@tailwind variants` are not supported/necessary
in v4, so we can safely remove them.
Input:
```css
@tailwind screens;
@tailwind variants;
```
Output:
```css
```
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