LearnWeb

.transparent_class {
    /* IE 8 */
    -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
    /* IE 5-7 */
    filter: alpha(opacity=50);
    /* Netscape */
    -moz-opacity: 0.5;
    /* Safari 1.x */
    -khtml-opacity: 0.5;
    /* Good browsers */
    opacity: 0.5;
}