.popup_bg { 
    background:rgba(0,0,0,0.8);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 999; 
}

.popup_box {
    background:#fff;
    width:960px; 
    margin:0 auto; 
    position:relative;
    top:50%;
    margin-top: -240px;  
    z-index:50;
}
.popup_box em.close { 
        display:block; 
        width:40px; 
        height:40px; 
        text-align:center; 
        position:absolute; 
        z-index:999; 
        right:0; 
        top:0; 
        cursor:pointer
}
.popup_box em.close img {
    width: 100%;
    height: 100%;
}
.popup_box video {
      display:block; 
      position:absolute; 
      top:0; 
      left:0;
      width: 100%;
      height: auto;
  }
@media (max-width: 960px) {
    .popup_box {
      width: 100%;
      top:50%;
      margin-top: -120px;  
    }
    .popup_box em.close {
      width:32px; 
      height:32px; 
    }
  }