Zen Classic and IE 6

I have a theme developed based on zen_classic, and for the most part it's been quite successful. There's one requirement I'm having trouble with, though. The page should be between 800 and 1028 pixels wide, and it is, everywhere but IE 6. In IE 6, it's full width.

I went back to an unmodified zen_classic and found the same thing to be true: the layout is full screen in IE 6. You can see it at http://md5.4j.incitedev.com/

I have written non-drupal css/html that accounts for the issues with IE 6 based on the tutorials at http://www.positioniseverything.net/articles/jello.html and I kind of understand its display issues, but I'm unable to figure out how to implement it with Zen Classic.

I've searched drupal.org, but I'm not finding any guidance on this particular problem, and sure I'd appreciate any pointers people might have.