Transparent & semi-transparent dropdown menus in Son of Suckerfish

Note to remind myself that in the end what seems to work best is for IE6 to use a gif and set the div’s opacity, and in the rest just use a png. The AlphaImageLoader doesn’t let you position backgrounds so there’s no point trying to cram it all in. Fixed width stuff too, but doesn’t really matter if there are only 2 dropdowns.