Chris Mills shows how to use flexbox combined with Modernizr to serve different styles to browsers with differing levels of flexbox support, providing the best level of cross browser support currently available.
Colt McAnlis shows how CSS properties directly affects your page paint times.
TJ VanToll has compiled a complete list of the pseudo-elements available in Trident, Gecko, and WebKit.
Gabriele Romanato shows how to use CSS-generated content to embellish your layouts with strings and graphics.
Martin Gittins shows how to create a simple icon font using IcoMoon.
Roger Johansson explores the different ways you can create responsive drop shadows.
If you’re using an interactive element that moves when you click it, make sure that you don’t change the clickable area of the element when interaction actually happens.
Quite nice and detailed overview of CSS selectors.