마스크 레이어로 팝업 비디오 효과를 구현하기 위한 js 클릭 버튼의 코드 예제 분석

<p class="main">
  <a href="javascript:;" class="video" id="video"></a>
</p>

 <p class="video-btn" id="video-btn">
   <p class="video-area" id="video-area"></p>
   <a class="video-shut" id="video-shut">x</a>
 </p>
 <p id="shadow"></p>

.video-btn{
      position: absolute;
      width:600px;
      height: 300px;
      background:black;
      top:50%;
      left: 50%;
      margin-top: -150px;
      margin-left:-300px;
      display: none;
      z-index: 101;
    }
 .video-area{
      float:left;
      width:500px;
      height: 300px;
      background:red;
    }
.video-shut{
      height:100px;
      width:100px;
      font-size:40px;
      color:pink;
      float:left;
      text-align: center;
      /*line-height: 50px;*/
      background: yellow;
      display: block;
      padding-top:30px;
    }

 #shadow{
      position: absolute;
      opacity: 0.5;
      filter:alpha(opacity=50);
      bottom:0;
      left: 0;
      right: 0;
      top: 0;
      background:black;
      z-index: 100;
      display: none;
    }