CSS
W3C - CSS Snapshot 2018
Understanding the CSS Specifications
Centering in CSS: A Complete Guide | CSS-Tricks
Aspect Ratio Boxes | CSS-Tricks
A Complete Guide to Flexbox | CSS-Tricks
Piccalilli - Dang Spicy Tutorials - Piccalilli
The Shapes of CSS | CSS-Tricks
10 of the best CSS animation libraries.
CSS reset. Follow me on the twitters for more tips: https://twitter.com/davidwells