non-scrolling header area in foreground not background

i've been having the best time re-creating a clunky old non-WP site i designed a couple of years back, but now using atahualpa instead. LOVE THIS THEME! i never use any other theme, you just DON'T HAVE TO

i have a feeling what i'm asking may not be possible.. can't hurt to ask if anyone has any thoughts. i have a thin bar across the top of the page, which needs to stretch across the entire screen. i've put it into the background, and it looks perfect. i only wonder if there is a way to have a non-scrolling version of it in the top foreground instead of the background? (when i set it to non-scrolling in the background, of course the rest of the page scrolls all over it, which isn't the idea!)

anyway : here's the page : http://blove.ca/2011

any thoughts, please do let me know!