CSS3 Opacity Declarations

/* opacity */
    -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=0)"; /* IE 8 */
    filter: alpha(opacity=0); /* IE 5-7 */
    -khtml-opacity: 0; /* Safari 1.x */
    -moz-opacity: 0; /* Netscape */
    opacity: 0; /* Good browsers */