I sympathize. Been doing webdev since 1998 (before CSS). Most CSS in the wild is just awful and virtually unmaintainable. I can't recommend highly enough that you and everyone else (the overwhelming majority) who feels the same way head to https://every-layout.dev to learn about "Axiomatic CSS". It explains and illustrates not just layout but virtually everything you need to know about leveraging standard CSS, building up from clearly-articulated and unimpeachable first principles. The axioms and examples on the free site are profoundly useful, and the $100 book / full site / component generator are more than worth it.

Disclaimer: No affiliation, just a grateful customer hoping these ideas catch on.