You can't span a single image across all frames because they
individual pages. You can fake it by lining up the background
you know the exact frame dimensions. For example - consider a
2-frame design with a left navigation frame of 200px and a
frame taking up the rest of the width of the browser window.
frame would house the background image in full. Of course -
see the left 200px of it. Then in the content frame, use the
background image, but offset it by 200px to the left with