kyleemckinney on "Over-riding theme's !important tag"

I'm using Firebug and going thru each section of the Atahualpa theme - OMG, it's taking a LONG time, but I love being able to change virtually everything! Anyway, I'm trying to change the font in the menu to bold. I don't know if that's what I'm looking for or not, but the menu needs something, so that's my next step.
Problem is, font-weight: bold !important didn't do it, and I can't figure out which line to change. I've changed pretty much every line in that div, but it's just stubbornly refusing to change. I thought the source file had font-weight: 700!important but now I can't find it, so maybe that was one of my attempts to change it to bold.
The menu in question is at http://www.progressiveinsanity.com/test
Thank you for your help ...
~Ky