I went ahead and pulled the trigger on Ubermenu.
Can you give me the css that you use for Steam menus so I can apply it to Ubermenu's custom css override section? I want the best of both worlds :)
Whenever you want to identify or change the style of any part of the theme, use Chrome or Firefox+Firebug and right click on the area you want to change and choose Inspect Element. That will bring up a console that shows exactly which lines of CSS in exactly which files affect that element so that you can go in and change the style how you see fit.
Specifically for Steam's existing menus it would all be near the top of the style.css file, but the method explained above will get you exact line numbers.
I stand corrected: I understand completely how to use the inspector, but don't understand which elements I should be cutting and pasting after struggling with this for more than 12 hours.
A little hand holding please...?
That might be your issue - it's not just copying and pasting CSS because the markup is likely different for the ubermenu, meaning the same CSS can't be applied. It's going to require some knowledge of CSS to get working. If you need a developer to help you I recommend Microlancer.com.