Background not showing in Firefox

http://www.babytoupee.com/photogallery/main.php

I have created an new theme with a colored background. In IE the background shows. However, in Firefox the background color does not show.

If I remove the first line of the page:

<?xml version="1.0" encoding="iso-8859-1"?>

Then the background shows but this causes other problems. Therefore, I think the background issue is related to the XML doc type.

Does anyone know what the proper way to configure backgrounds is for this type of XML page?

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