If we could do it over, knowing that we'd eventually get to this point, would https://en.wikipedia.org/wiki/JavaScript_Style_Sheets have been the better path?
Probably not. There is a lot of optimizations browsers do to make the stylesheets super fast[1], and I think quite a few of those rely on CSS not being Turing complete.
1: https://hacks.mozilla.org/2017/08/inside-a-super-fast-css-en...
If I had a time machine I would go back and ensure that DSSSL (https://en.wikipedia.org/wiki/Document_Style_Semantics_and_S...) was the standard that got up.