A Complete Guide to Custom Properties
Everything important and useful to know about CSS Custom Properties. Like that they are often referred to as “CSS Variables” but that’s not their real name.
Bourbon Sass Mixins Library
A simple and lightweight mixin library for Sass. Bourbon is a library of sass mixins that are designed to be simple and easy to use. No configuration required.
min-device-pixel-ratio test
What’s your device’s min-device-pixel-ratio?
Home - Scalable and Modular Architecture for CSS
A brilliant and inspiring book. Not only useful, but fun to read too. Full of good tips and ideas. I love the approach.
All The Cheat Sheets An Up To Date Web Designer Needs: CSS3, HTML5 and jQuery
Awesome tutorials to master responsive web design
Vendor-prefixed CSS Property Overview « Peter Beverloo
60 Useful Web Developer Cheat Sheet Collection
25 Useful Html5 Cheat Sheets and Tutorials For Web Developer
11 Free Tools Important For Web Developers
Prefixr
Generate cross-browser CSS
Best Collection of Useful CSS Tools for Developers
The Roles Model | Accessible Rich Internet Applications (WAI-ARIA) 1.0
Handy for reference
Responsive Web Design: Helpful Articles, Techniques & Tutorials
Flat, simple icons for interface design
One Page Apps I Actually Use
8 Fast and Furious Tools to speed up your CSS and HTML Coding Time
12 Useful and Free Downloadable Web Design Books
Handy references by Speckyboy Design Magazine
Safari Web Content Guide
Handy reference for developing Web apps that run on Mobile Safari