An Interactive Guide to Flexbox

[mischah]

This is truly awesome: https://www.joshwcomeau.com/css/interactive-guide-to-flexbox/

Problem: We already have 7 resources in the section »Flexbox« 😱 See https://github.com/micromata/awesome-css-learning#flexbox

So I wonder if this should replace the first or second item? Or should we get rid of some of the flexbox games?

//cc @nicolaisueper @uschmidt