Panda CSS
Segun Adebayo (of Chakra UI fame) has just announced the release of Panda CSS, a new CSS-in-JS library that generates utility styles at build time (instead of runtime).
This looks like just the thing I've been wanting, you can still create dynamic styles like you can with Tailwind, but defining styles in objects rather than doing string concatenation makes the story around customising and overriding styles much simpler.