CSS

Animate.css

A cross-browser library of CSS animations. As easy to use as an easy thing.

CSS PREprocessors

One-stop reference for the three most popular CSS Preprocessors – Less, Sass, and Stylus.

Can I use

Provides up-to-date browser support tables for support of front-end web technologies on desktop and mobile web browsers.

Ultimate CSS Gradient Generator

A powerful Photoshop-like CSS gradient editor.

CSS-Tricks

Dedicated to the world of CSS and related technologies. Snippets, videos, tricks and tutorials.

CSS3 Click Chart

CSS3 Browser Support and Information

Codrops

Web design and development blog that publishes articles and tutorials about the latest web trends, techniques and new possibilities.

CSS3 Generator

Generate Border Radius. Box Shadow. Text Shadow. RGBA. @Font Face. Multiple Columns. Box Resize. Box Sizing. Outline.