CSS transparency/opacity (IE included)

                                          .selector {
    ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
    /* internet explorer 8 */	filter: alpha(opacity=50);
    /* internet explorer 5~7 */	-khtml-opacity: 0.5;
    /* khtml, old safari */	-moz-opacity: 0.5;
    /* mozilla, netscape */	opacity: 0.5;
    /* fx, safari, opera */
}