Reminds me of CSS Diner - https://flukeout.github.io/
I first started learning webdev in 2005 and just a decade later the number of educational resources blows my mind.
That said, try "flexbox game learning" in duckduckgo ;-) - https://duckduckgo.com/?q=flexbox+game+learning&t=ffhp
FWIW: DuckDuckGo ROCKS! DuckDuckGo bang syntax ROCKS! Even when DuckDuckGo itself doesn't rock, it let's you easily, and slightly more privately, search other search engines https://duckduckgo.com/bang so It ROCKS even when it doesn't ROCK!
Reminds me of CSS Diner - https://flukeout.github.io/