Pseudo classes missing from extracted CSS?

I noticed `extractStyles` and `inlineStyles` does not produce any pseudo classes. E.g. `a:hover` was left out.

I realize this is all not `usus` specific (but CSS Coverage) but I was wondering why. Also: for critical styles I would expect these to be included.

Start by tracing the extractStyles and inlineStyles entry points and reproduce the reported omission with a selector such as a:hover. Review how extracted CSS is filtered, then verify that the intended pseudo-class rules are retained for critical styles and add coverage for the reported case.

Written by the indexing model from the issue text.