CSS applied to SELECT/OPTION elements

Tests carried out with Opera 6.05, IE 6, Mozilla 1.1 and Netscape 4.08. All in Windows XP. Page background colour is to try and discover what Netscape 4 was doing with the missing elements...

Note that in Mozilla, styles applied to OPTION are only visible when the SELECT element is 'open'. In IE6 they are always visible.

No styles:
border: none; No effect in Opera 6 and IE6. Changes border to black in Mozilla. Converts select element to plain text in NN4. Removes border in Opera 7.
border: 4px solid red; No effect in IE6. Adds extra border around element in Opera 6. Changes border to red in Mozilla. Converts select element to plain text, but does add red border to that, in NN4. Changes border to 4px red in Opera 7.
border: none; on OPTION No effect in IE6, Opera 6, Opera 7 or Mozilla. Makes element vanish, though space is still reserved, in NN4.
border: 4px solid red; on OPTION No effect in IE6 or Opera 6, Opear 7. Adds red border around each option in Mozilla. Makes element vanish, though a series of red borders are shown, in NN4.
background-image No effect in IE6, Opera 6, Opera 7 or Mozilla. Converts select element to plain text, but does add background image to that, in NN4.
background-image on OPTION No effect in IE6, Opera 6, Opera 7. Works in Mozilla. Makes element vanish, but space is still reserved, in NN4.
background-color: No effect in Opera 6 and NN4. Works in IE6, Opera 7 and Mozilla.
background-color: on OPTION No effect in Opera 6, Opera 7 and NN4. Works in IE6 and Mozilla.