It's very difficult to see the problem; I wouldn't have noticed if you hadn't posted about it. However, I notice that your stylesheet.css has
background: url(../../../../images/bkg1.gif);
which should repeat in both directions by default, and it is doing that, but if you add
background-repeat: repeat;
see whether that makes any difference.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.