Where are good places to start diving into CSS?

To clarify on the question, I've been a dev for 2.5-3 years now and I feel like CSS is something that I've been just glossing over. I can get stuff done with it, but it always seems to be something I struggle with. I believe that knowing what's possible with CSS will help inform me on how to better structure and write my front end code.

CSS Grid is high up on the priority list, and I know some resources for that, but are there any good talks, tutorials, references (MDN is an obvious one), or articles that really show the true power of CSS? I plan on just creating things as well as scouring Codepen posts, so those would also count as great sources of it in action.