I recently changed the default background colour on Firefox from white to grey so that I could check the transparency on some images before uploading them to the site. I didn't bother to change the colours back because I didn't think I needed to. I expected that these days most web pages would define a background colour if they needed one.

The normal google home page looks ok but some of the other pages seem to expect the default white. The Google logo and icons appear with white backgrounds but the rest of the page is defiantly grey.