That is indeed one of the major downsides of this template, due to transperency in the images, to allow perfect shadows on changing backgrounds, it is very hard to make the width scalable, however, I'm currently working on a new version which should fix this issue
By the way, you may want to create a new background image for the thumbnails so the background color fits that of your page, unfortunately IE does not do well with transparrent background images, therefore in order to apply the same technique as used on the front page on the thumbnails, one would have to hack the pixelpost index file, which obviously isn't a desirable solution for a template.