CSS formatter

Puts each declaration on its own line and indents nested blocks, or strips it all back out. Minifying also removes comments and the final semicolon in each block.

Dropping the last semicolon is safe and is what every minifier does — CSS needs a semicolon between declarations, not after the last one. Two things this deliberately does not do, because both change behaviour: it does not merge duplicate selectors, since the cascade means order matters and merging can change which rule wins, and it does not shorten colours or units. A minifier that reorders a stylesheet to save bytes trades a real risk for a small gain, and gzip recovers most of that gain anyway.