Well, I would check to see if your background setting is in the pagebody or the body.

If the background setting is only in the body, or only in the pagebody (or even another wrapping div) then it might only effect a certain area of the page, defined by the width/height of that div.

So check to see if it says

body { 
       background:#FFF;
}

or

.pagebody {
       background:#FFF;
}

Generally you want the background color in the pagebody, but you can try both and see what happens. Also, make sure that these two settings aren't different colors.