SOURCE

<div class="tab-father">
  <li class="tab-item">控制</li>
  <li class="tab-item">指令</li>
</div>

li{
  list-style:none;
}
.tab-father{
  width:200px;
  background:#fff;
  text-align:center;
  li{
    display:inline-block;
    margin: 0 4px;
    &:first-child{
      border-bottom: 1px solid blue;
    }
  }
}