.video_div{
    width: 802px;
    margin: 0 auto;
}
.video_div h2{
    text-align: center;
    font-size: 24px;
    margin-top: 40px;
    margin-bottom: 45px;
    font-weight: bold;
}
.video_ul{
    width: 802px;
    padding-bottom: 80px;
}
.video_ul li{
    position: relative;
    float: left;
  
}
.videolist{
    width: 380px;
    height: 280px;
    margin-bottom: 20px;
    overflow: hidden;
}
.videolist img:nth-child(1){
    width: 380px;
    height: 280px;
}
.video_ul li:nth-child(odd){
    margin-right: 40px;
}
.videoed{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
    cursor: pointer;
    z-index: 98;
}
.video_ul .videos{
    display: none;
    position: fixed;
    top: 50%;
    left: 50%;
    width: 802px;
    transform: translate(-50%,-50%);
    z-index: 100;
}

.mask{
    display: none;
    width: 100%;
    height: 100%;
    position: fixed;
    z-index: 99;
    background: rgba(0, 0, 0, .75);
    left: 0;
    top: 0;
}
body{
    background: #f8f8f8;
}
.content{
    width: 1200px;
    margin: 0 auto;
    padding-top: 120px;
}
.content-rt{
    float: right;
    padding: 0 18px;
    width: 915px;
    background: #fff;
   
}
.cont-nav{
    height: 60px;
    line-height: 60px;
    font-size: 18px;
    border-bottom: 1px solid #f2f2f2;
}
.cont-nav a{
    color: #0c7ed9;
}