I learnt CSS in a similar way. I'd take Photoshop designs and try to recreate them in vanilla HTML + CSS:

https://jsfiddle.net/umaar/YNA5V/

https://jsfiddle.net/umaar/fu4TT/

I'd even make 3d graphics of things like the HTML5 logo: https://i.imgur.com/kuEYpSV.png

I posted this all to a community called "Forrst" (think of it like twitter, but curated for developers and designers).

I spent time giving feedback on other peoples work, I tried to ask insightful questions https://twitter.com/umaar/status/823915022917271552 to have an open discussion, I spent hours replying to comments every few days.

Then one day, Forrst got acquired by Zurb https://zurb.com/blog/zurb-acquires-forrst and later on it got shut down, and with that, I lost access to huge amounts of my work which I hadn't stored anywhere else (some stuff has been archived online, but not everything).

When it comes to web development tips, I now self-host on my own website and it's a really good feeling knowing that it'll be preserved: https://umaar.com/dev-tips/