the logo block is class logoBlock
the header is unique, and has the id of header #header
The #header, will span 100%
Code:
#header {
background-image: url('http://cdn.xenfans.com/valentines/bgh.png');
background-position: top left;
background-repeat: repeat-x;
}
That's what I use on the Valentines theme to get the repeating header's background to show.