Working with modern CSS is such a joy, and increasingly as time goes on I'm replacing huge chunks of JS with CSS which is a little boon in itself. Honestly, my only complaint is how long I have to actually wait to use new features.
Nesting and @layers make maintaining CSS drastically easier than it once was as well.
I agree. And I don't even use layers yet. I keep specificity roughly in mind and narrow my selectors using nesting properly to only affect what I want the rules to style. Do I make mistakes? Sure, but they are easy to fix. Make selectors specific enough and think about whether the rule you are writing is something general or just something for this one component on the page, and it is eeeeasy to not make a mess these days.