All posts, whether they are written by Chris Coyier or a guest blogger, are very clear and well explained. Each example has code snippets with easy-to-follow explanations of the code and theory behind the specific concept. Possible issues you may run into with the code are often addressed, so you know how to tackle bugs that may pop up.
CSS-Tricks is extremely active, being updated every day or two with a new blog post. Despite the frequency of the posts, the quality always remains high.