For many web developers, A Complete Guide to Flexbox from CSS-Tricks.com is a pillar of our web developer reference material. It’s my externalized memory on how the flex feature of CSS works. I don’t have to remember how it works because I know I can look it up there. You can even download a poster version to hang on the wall.

Now there’s another great reference An Interactive Guide to Flexbox by Joshua Comeau. An instant classic.