FireBug is a wonderful tool for web development. You guys probably already know about it, but perhaps not. It is a FireFox extension that gives you a lot of details on CSS and Ajaxy errors. For instance, just loading http://www.notcomet.com/compose shows 49 errors in FireBug. Most of them appear to be CSS:
If I click on one of the css file names in the right column there, it even pops up the relevant CSS file with the line highlighted. It's heaven. FireBug has lots of tools to help you drill down on CSS issues, like Inspect Element which lets you pick an element on the webpage and it displays the corresponding CSS and DOM underpinnings.
Btw, don't feel bad about 49, Check out what gmail does:







