IE8中背景透明度兼容解决

background:#000000; /*支持rgba的浏览器*/-khtml-opacity:0.6;-moz-opacity:0.6;filter:alpha(opacity=60);filter:"alpha(opacity=60)";opacity:0.6; filter: progid:DXImageTransform.Microsoft.Alpha(opacity=70);/*兼容ie8及以下*/