CSS preprocessors are fine. Processors only understand binary but noone programs in binary today. If CSS become the binary of tomorrow, it's fine.

Inlining CSS is stupid, it makes your page bigger, less flexible, doesn't use browser caching technics, and didn't solve the problem at all (or make it worse...).

CSS with Javascript is even worse, as it will be slow as fuck, hard to maintain, and equivalent to directly write CSS by hand anyway.

flex-boxes, box-model, table display, and more... solve most of problems you will ever had.