.video_appbox{ position:fixed; width:100%; height:100%; top:0; left:0; z-index:1000; display:none;z-index: 999999999;}
.video_appbox .video_t{ left:10%; top:15%; position:absolute; height:70%; width:80%;   z-index:2; background:#000;}
.video_appbox .mask{ position:absolute; z-index:1; left:0; top:0; width:100%; height:100%; background:rgba(0,0,0,0.5);}
.lt9 .video_appbox .mask{filter: progid:DXImageTransform.Microsoft.Gradient(GradientType=0, StartColorStr="#88000000", EndColorStr="#88000000");}