Flexbox is awesome, but can be hard to understand. Here’s a series of interactive examples showing practical ways to use Flexbox for building UI components…
A look at the common features and differences between Flexbox and CSS Grid Layout….
A useful reference for working with CSS Grid Layout…
There are lots of ways to generate critical CSS and this tutorial looks at how it can be done using PostCSS and PostCSS-Split…
A great article on learning to replace HTML grids with Susy Grids or Flexbox…