New browsers are good to opacity, but old ones need some special codes to have transparent elements.
.opacityBlock {
-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=20)"; /* for IE8 */
filter:alpha(opacity=20); /* for IE7 */
-moz-opacity:0.2; /* Old Mozilla */
-khtml-opacity: 0.2; /* Safari 1 */
opacity:0.2; /* New Browsers and IE9 */
}Remember that opacity will have an effect on all child elements inside opacity changed element.
