.a_test{
            display: inline-block;
            width: 310px;
            line-height: 20px;
            background-color: rgba(0,0,0,0.5);
            color: #fff;
            text-align: center;
            position:relative;
            margin-top: -26px;
            padding: 3px 5px;
            overflow: hidden;
            margin-bottom: 0;
        }
        #video_s {
            position: relative;
        }
        .a_test2{
            display: block;
            width: 310px;
            line-height: 20px;
            height: 20px;
            background-color: rgba(0,0,0,0.5);
            color: #fff;
            text-align: center;
            position:relative;
            bottom: 26px;
            padding: 3px 5px;
            overflow: hidden;
            /*z-index: 999;*/
        }
        #nav {
          width: 1023px;
        }