I think I'm trying to do something similar. My site is http://theboatgalley.com
and the problem occurs when looking at the site in Firefox or Chrome (haven't checked with other browsers) with a wide-screen monitor and no bookmarks or anything taking up width.
I'm using fluid width at 100%, with a max-width of 1200 to limit resizing. BUT I'd like to eliminate the max-width restriction on just the header, so that the orange bar will go all the way to the left and right sides of the screen, with the content then in the center. A good example of what I want to achieve is to look at Facebook, where their dark blue strip goes across the whole width, with the real content in the center at what I assume are their max-width settings.
I'm attaching screen shots to show what I'm talking about (I cropped them just to show the upper left corner to keep the size reasonable). It's a little hard to see the problem here, because the background for this reply is white and so is the problem area, but just know that there's a white area to the left of the orange bar if you look at my site on a wide-screen monitor over 1200 pixels.
Is there any way to do this?