I haven't edited eBay templates so I don't know how it's done, but it should be easy using the appropriate CSS. On the other hand, www.splashpaintball.co.uk is depressingly devoid of CSS and standards so it might be hard to convert.
It's because the ebay page is much longer, in the css put
background: url() top;
and it should only have the cut off once in the middle rather then twice