Atahualpa menu bar span entire page????

Atahualpa 3.7.7 is a great theme, however I am having trouble trying to take my blue menu bar and have it span the entire page. It is currently set to at 1000px in width as is the header.

How do I get the bar span the entire page? I was told I would need an background image. I created an background image that is w:10 h:125

But I have been unable to get it to work or show the image as a background.

Here is my code:
html{

background: url('/images/bg_color.gif');
background-repeat: repeat-x;
background-position: center top;
height:125px;
}


Below is my url:
http://vintageconsignor.com/

Can someone please assist me please?

Thxs.....