This PR fixes an issue where `!important` is added to declarations that
define CSS variables. The `!important` should only be added to the other
declarations.
Before:
```css
.ease-out\! {
--tw-ease: var(--ease-out) !important;
transition-timing-function: var(--ease-out) !important;
}
```
After:
```css
.ease-out\! {
--tw-ease: var(--ease-out);
transition-timing-function: var(--ease-out) !important;
}
```
Fixes: https://github.com/tailwindlabs/tailwindcss/issues/16664
b9af722d13