I consider myself pretty well-versed in the use of CSS, the browser issues associated with it and the ways around those issues. But every time I read something from Eric Meyer I learn something. He is a master.
Eric Meyer on CSS contains an amazing amount of knowledge explained through 13 projects. Though the work details some CSS which isn’t currently supported, the details are practical and lay a good foundation for the use of the technology. Most of the projects do render beautifully on IE 6 and Netscape 6, and I have incorporated many of the tips in this site and others I work on.
There is a great companion Web site as well which provides errata and all of the code detailed within the book.
If you are responsible for Web-based user interfaces this is a must have. One note, this book won’t teach you CSS/DHTML, it assumes you have the basic knowledge of the technologies and their use. It is labeled “Intermediate – Advanced”.