CSS felt "solved" for me when the React team introduced inline styles. I've been using them ever since and it has made styling a breeze. I know people balk at inline styles, but I still haven't heard a convincing argument as to why they are a bad thing.
Lots of rule duplication and no pseudo-selector support with inline styles. If you like using inline styles, I think you'd like CSS-in-JS, because it has a similar feel when writing components with the benefit of deduped atomic classes as critical CSS + pseudo-selector support.
