<dl>
  <dt>1-1. 浮动布局之设置overflow实现</dt>
  <dd class="box-1-1">
    <div class="layout">
      <span class="left">分类列表区域</span>
      <span class="right">主要内容区域<p>这是p标签的内容</p></span>
    </div>
  </dd>
</dl>

dl{
  padding: 0;
  margin: 10px;
  dt{
    margin-top: 10px;
    font-size: 20px;
    color: #fff;
    background-color: #00c;
    height: 50px;
    line-height: 50px;
    padding: 0 10px;
  }
  dd{
    border: 1px solid #ccc;
    margin: 0;
    height: 200px;
  }
  .left{background-color: pink;display: inline-block; vertical-align:top; letter-spacing: normal;}
  .right{background-color: skyblue;display: inline-block;letter-spacing: normal;}
}
.box-1-1{
  .layout{
    height: 200px;
    letter-spacing: -.35em;
  }
  .left{
    width: 15%;
    height: 100%;
  }
  .right{
    width: 85%;
    height: 100%;
  }
}