You can view the CSS (or in other words, the style definitions) of any site on the web. An easy way to do this is with the Web Developers Toolbar. Go to CSS > View CSS or CSS > Edit CSS. Both of these methods will show you the styles for that particular page.
Note: The "Edit CSS" option has the additional advantage of allowing you to edit the styles and see how your edits affect the design. In case your curious: you are the only one who can see your edits. When you play around with the styles, it does not affect the real web site. When you refresh the page, all of your edits disappear.

This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 License.