Netscape versions 2.0 and above have a small idiosyncrasy
relating to background images with this element. The background image of the document
(if one is specified) is not used inside a square region surrounding the radio button.
If the document has a background color, it is used in the "non-radio" portion of
this square instead. This does not happen before Netscape 2.0 - it appears that
form field rendering was changed for version 2.0.
BODY uses BGCOLOR=red to create extreme contrast to exhibit the behavior