This is all great, but while the internet is filled with auto-playing videos and invokes to external scripts from google, meta, amazon and who knows where, the example on this page is about saving... 148 bytes? Does minifying CSS really make a big difference, in the end? I'm guessing that a page with a serious CSS payload (say, over 100k) already has more serious weight problem elsewhere.

LightningCSS[0] is better and faster, unless something has changed.

https://lightningcss.dev/

Is there a tool that can remove unused CSS while considering static HTML?

What I have in mind is a tool that I throw a CSS file and a bunch of static HTML files at, it will try to apply each CSS rule to the HTML like a browser would and remove all the rules that don't apply.

I don't expect it to ascertain if a rule had visible effects. I also don't expect it to consider JavaScript. Just plain CSS and static HTML. It doesn't look to me like CSSnano or LighteningCSS could do that.

Eh, even on this example, most of the gains come from simply removing the comments (something that can easily be done with `cpp -E -P <in.css >out_cpp.css` or regexps since CSS doesn't allow comment nesting) on most UNIXes.

Here's a more complete result adding brotli and the aforementioned cpp version:

  $ gdu -b *.css *.css.gz *.css.br | awk '{if (NR % 3 == 1) {ref = $1; print} else print $0, "(" $1 - ref ")"}'
  623 in.css
  197 out.css (-426)
  355 out_cpp.css (-268)
  345 in.css.gz
  185 out.css.gz (-160)
  235 out_cpp.css.gz (-110)
  284 in.css.br
  141 out.css.br (-143)
  177 out_cpp.css.br (-107)

cssnano has had some complicated ownership turnover[0], I'm glad to see someone took the mantle again though.

I do find that CSSO[1] with structural optimizations can be more effective still, perhaps that will be less true overtime though.

I think once lightning CSS is more stable (in particular, some bugs are addressed around ordering) it will be the clear winner in this space though.

[0]: https://github.com/cssnano/cssnano/issues/833

[1]: https://github.com/css/csso

People need more things that can be discovered. Everyone reinvents the wheel rn.

Why keep background-position, if background overrides it anyway?