Head First HTML with CSS & XHTML

Our Favorite CSS Design Sites

CSS Zen Garden: The Beauty in CSS Design :: Graphic artists create some fantastic designs for the Zen Garden by changing only the CSS.
A List Apart :: explores the design, development, and meaning of web content, with a special focus on techniques and benefits of designing with web standards.
css/edge :: Eric A. Meyer's CSS site with a selection of examples.
CSS Beauty :: A showcase of well-designed CSS based websites from around the world. It's a great place to find inspiration for your own designs.
CSS Vault :: Another great site to explore for inspiration. It also has links to articles about CSS design.
Listamatic :: Everything you ever wanted to know about how to style lists.
Position is Everything :: If you want to try a new layout using CSS, this is a good place to start. This site has just about everything you'll need for a variety of different layouts, including the workarounds you'll need for buggy browsers.
The CSS Spec :: Very technical, but hey, it's the definition of CSS. This is the official documentation for CSS at the W3C.