The Stream of Consciousness Has Its Headwaters In My Mouth

I've been trying to learn XHTML and CSS (my HTML skills are ca. 1996) and I've been busting my ass over this particular bit of code in Stylin' with CSS. It's the code for the horizontal menu. No matter what I tried in the way of tweaking, the Dreamweaver MX 2004 had the menu wrapping. It also had the menu div encroaching on the div below it. I tweaked, I copied, I pasted, I watched more CSS tutorials. Nothing was helping. I parsed it bit by bit and couldn't figure it out. Finally, having heard in a sitepoint.com tutorial that the design view in Dreamweaver is capable of bugs, I decided to preview in the browser and see if it was screwing up there as well. It wasn't! Oh man, if only I'd previwed earlier...