盒子垂直居中

• 代码

 	.wrap {
      width: 500px;
      height: 500px;
      border: 1px solid #000;
      margin: 0 auto;
      position: relative;
    }

    .son1 {
      width: 100px;
      height: 100px;
      background-color: red;
      position: absolute;
      left: 0;
      top: 0;
      bottom: 0;
      right: 0;
      margin: auto;
    }
    <div class="wrap">
    	<div class="son1"></div>
  	</div>

• 效果