It's simple and obvious, but few people actually do it: read the CSS spec. Learn the rules for specificity, for vertical margin collapsing, for positioning and

It's simple and obvious, but few people actually do it: read the CSS spec. Learn the rules for specificity, for vertical margin collapsing, for positioning and stacking, for forward-compatibility. I know way too many front-end devs/designers who only learned from shitty second hand tutorials, and it always shows.