This PR inserts the `@import` in a more sensible location when running
codemods.
The idea is that we replace `@tailwind base; @tailwind components;
@tailwind utilities;` with the much simple `@import "tailwindcss";`. We
did this by adding the `@import` to the top of the file.
While this is correct, this means that the diff might not be as clear.
For example, if you have a situation where you have a license comment:
```css
/**! My license comment */
@tailwind base;
@tailwind components;
@tailwind utilities;
```
This resulted in:
```css
@import "tailwindcss";
/**! My license comment */
```
While it is not wrong, it feels weird that this behaves like this. In
this commit we make sure that it is injected in-place (the first
`@tailwind` at-rule we find) and fixup the position if we can't inject
it in-place.
The above example results in this:
```css
/**! My license comment */
@import "tailwindcss";
```
However, there are scenario's where you can't replace the `@tailwind`
directives directly. E.g.:
```css
/**! My license comment */
html {
color: red;
}
@tailwind base;
@tailwind components;
@tailwind utilities;
```
If we replace the `@tailwind` directives in-place, it would look like
this:
```css
/**! My license comment */
html {
color: red;
}
@import "tailwindcss";
```
But this is invalid CSS, because you can't have CSS above an `@import`
at-rule. There are some exceptions like:
- `@charset`
- `@import`
- `@layer foo, bar;` (just the order, without a body)
- comments
In this scenario, we inject the import in the nearest place where it is
allowed to. In this case:
```css
/**! My license comment */
@import "tailwindcss";
@layer base {
html {
color: red;
}
}
```
Additionally, we will wrap the existing CSS in an `@layer` of the first
Tailwind directive we saw. In this case an `@layer base`. This ensures
that utilities still win from the default styles.
Also note that the (license) comment is allowed to exist before the
`@import`, therefore we do not put the `@import` above it. This also
means that the diff doesn't touch the license header at all, which makes
the diffs cleaner and easier to reason about.
---------
Co-authored-by: Philipp Spiess <hello@philippspiess.com>
4f8ca556cf