CSS2 - opacity
If you want opacity to work in all IE versions, the order should be:.opaque { -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=50)"; //...
IE9, Opacity, and Alpha – IEBlog
opacity: 0.5; filter: alpha(opacity=50);} Example Best Practice Code ...filter:alpha(opacity=50); /* IE fallback support for IE7, IE6, IE5....