Yes, CSS variables. Defining a preset of variables on :root for sizes and color ranges goes a long way.

The design philosophies behind Tailwind are sound, but like so many I dislike the technical implementation. I feel like there is a lot of halo effect happening with Tailwind where judgement of technical merits is influenced by judgement on visual merits.

You may use CDN build of UnoCSS (16k GH stars) https://unocss.dev/integrations/runtime which generates styles on the fly for 80% of benefits with 0% build steps (even with regular HTML)

It does have quirks compared to build variant, so if you use a framework, using it in a build step may be better, it'll still be much lighter then tailwind

Yes: https://unocss.dev/

You can even use it directly in runtime https://unocss.dev/integrations/runtime

Give 60% to someone else