Browser display differences

Here’s a fun one. I’m loading my blogsite (using Default Theme) into an HTML object which is part of my Index.html file or my Home page whichever you prefer. In the Index.php for the theme I editted it thru Dashboard and removed the get header and get sidebar commands since I only want to display the blog posts. This works fine when my site (https://www.hawaiisportsrap.com) is called on from IE (7 or 8). If I call on it from Firefox 3.6.3, the white background that’s supposed to be there and shows in IE is either not displayed or it could be transparent. Any idea what might be causing this?

Thanks in advance
Doc