圣杯布局

  <div class="warp">
      <div class="content">
      </div>
      <div class="left">left</div>
      <div class="right">right</div>
    </div>

<style>
      * {
        padding: 0;
        margin: 0;
      }
     
      .warp {
        /* width: 100vw; */
        height: 500px;
        margin: 0 auto;
        padding: 0 200px;
      }
      .content,
      .left,
      .right {
        float: left;
        height: 100%;
      }
      .content {
        width: 100%;
        background: pink;
      }
     
      .left,
      .right {
        width: 200px;
      }

      .left {
        position: relative;
        background: green;
        margin-left: -100%;
        left: -200px;
      }
      .right {
        position: relative;
        background: yellow;
        margin-left: -200px;
        right: -200px;
      }
    </style>

优点:不用增加dom节点 缺点:会变形