There is a great website called the CSS Zen garden. Essentially it is designed to illustrate the possibilities of using CSS based design. Designers and developers are invited to download the html and CSS files, and then create a new look using just those files and changing the CSS. Here are samples of the dozens and dozens of submitted designs.
The first is the original “Zen garden” by Dave Shea and Molly Holzschlag, then “Zen Army” by Carl Desmond, “Floral Touch” by Jadas Jimmy and “Retro Theater” by Eric Roge.
If you are looking to start learning how to use cascading style sheets and want a good place to start, this is it. The possibilities are endless.