While I haven’t read his book [0], I always enjoy the articles by Ahmad Shadeed [1][2]. The ones that focus on how big websites like Facebook implemented specific functionality and how he would have tackled it are a great resource in advanced CSS.
I would also recommend the “thinking of ways to solve…” gui challenges [3] YouTube videos and web.dev articles by Adam Argyle.
Others have mentioned Josh W Comeau who definitely puts out good articles as well.
In the end, as with everything programming related it comes down to actually building stuff and getting your hands dirty. CSS is really something you can only get better at by running into real world issues and discovering its quirks.
I would also recommend the “thinking of ways to solve…” gui challenges [3] YouTube videos and web.dev articles by Adam Argyle.
Others have mentioned Josh W Comeau who definitely puts out good articles as well.
In the end, as with everything programming related it comes down to actually building stuff and getting your hands dirty. CSS is really something you can only get better at by running into real world issues and discovering its quirks.
[0] https://debuggingcss.com/
[1] https://www.ishadeed.com
[2] https://www.defensivecss.dev
[3] https://youtube.com/playlist?list=PLNYkxOF6rcIAaV1wwI9540OC_...