Background color problems in nested divs

OK, so I just don't get this... I've got a wrapper div, with two columns inside it. The wrapper's background is white, but the empty space under the right column is orange (body background color) rather than the wrapper's white. In Dreamweaver's design view, the wrapper div looks like it has no height, and so does not contain the other two divs. Why? :confused:

Thanks in advance.

http://globaljusticegame.mrap.info/newdesign/index.html
http://globaljusticegame.mrap.info/newdesign/gjgstyle.css

http://bonrouge.com/2c-hf-fixed.php

Thanks for the link. I went and added background-color: #FFF; to the largest wrapper, rather than a sub-wrapper. Voila!