milo,

I'm REAL busy today, but I had a couple of minutes to spare, so I done you some "quick & dirty" css just to get you started. It REALLY is dirty too, so you'll have to correct things, as I just added these lines to the very bottom of your stylesheet, making them override previous code. Anyway, this should get you on your way, anyway:

Code:
.col_1.firstcolumn, .dropdown_1column {max-height: 500px; width: 874px; background: skyblue!important; margin-top: -5px;}

div#wrapper_menu>ul>li>div>div>ul>ul>li>ul {background: black!important; z-index: 1000;}
See?...............Told you it was "dirty". Also, if you notice, to make sure you know which column is which, I've left "named" colors there for you.

Sorry so quick, sorry so dirty, but hope it helps get you started.