This PR is an optimization where it will not emit empty rules and
at-rules. I noticed this while working on
https://github.com/tailwindlabs/tailwindcss/pull/16120 where we emitted:
```css
:root, :host {
}
```
There are some exceptions for "empty" at-rules, such as:
```css
@charset "UTF-8";
@layer foo, bar, baz;
@custom-media --modern (color), (hover);
@namespace "http://www.w3.org/1999/xhtml";
```
These don't have a body, but they still have a purpose and therefore
they will be emitted.
However, if you look at this:
```css
/* Empty rule */
.foo {
}
/* Empty rule, with nesting */
.foo {
.bar {
}
.baz {
}
}
/* Empty rule, with special case '&' rules */
.foo {
& {
&:hover {
}
&:focus {
}
}
}
/* Empty at-rule */
@media (min-width: 768px) {
}
/* Empty at-rule with nesting*/
@media (min-width: 768px) {
.foo {
}
@media (min-width: 1024px) {
.bar {
}
}
}
```
None of these will be emitted.
---------
Co-authored-by: Jordan Pittman <jordan@cryptica.me>
7f1d0970c3