[smarkov]

I highly recommend Josh's guide: https://www.joshwcomeau.com/css/interactive-guide-to-flexbox...

It goes over more advanced gotchas and tips in detail such as flex-basis, auto margins, min-width, etc.

[jeeyoungk]

This is one of the best thing I read; I thought I was pretty good at Flexbox (and its tailwindcss building blocks), but this scratched my itch on some theoretical foundations.