Looks pretty good!
There is just one problem with it I would say. The text for the Catbg and the Tabs are too light. They are white right now and when with yellow its hard to read. Thats pretty much the only thing about it.
Edit:
Also you don't have to have it so you have to add the table width in the headers. You can put that in the CSS just like this:
/* The main body of the entire forum. */
body
{
background-color: #FFFFFCC;
margin: auto;
width: 825px;
padding: 12px 30px 4px 30px;
Well I believe that would work for it.
