It’s fashionable to crap on tailwind in some css circles but nothing else has improved my CSS knowledge so quickly - it’s specifically when used with the tailwind plugin in vscode, it shows the underlying css in popups and it’s addictive to guess what the underlying css will be for a given utility class and then quickly check.

That said, flexbox froggy and the other grid garden game were fun. Also find myself regularly going for the css tricks reference page for both of these.