css透明兼容，opacity兼容

以前的兼容

.transparent_class {
-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=50)"; /* ie8 */
filter:alpha(opacity=50); /* ie5-7 */
-moz-opacity:0.5; /* old mozilla browser like netscape */
-khtml-opacity: 0.5; /* for really really old safari */
opacity: 0.5; /* css standard, currently it works in most modern browsers like firefox, */
}

现在的兼容

.transparent_class {
-ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=50)"; /* ie8 */
filter:alpha(opacity=50); /* ie5-7 */
opacity: 0.5; /* css standard, currently it works in most modern browsers */
}