SOURCE

  <h1>通过旋转的元素</h1>
  <div class="arrow">已处理</div>  
  <div class="arrow active">处理中</div>  
  <div class="arrow">未处理</div> 

    body {
      padding: 10px;
    }
    .arrow {
      position: relative;
      display: inline-block;
      padding: 6px 16px 6px 30px;
      margin-right: -4px;
      text-align: center;
      white-space: nowrap;
      vertical-align: middle;
      background-color: #ddd;
      cursor: pointer;
      user-select: none;
      color: #666;
    }
    .arrow.active {
      background-color: #5bc0de;
      color: #fff; 
    }
    .arrow::before, .arrow::after {
      content: '';
      position: absolute;
      top: 5px;
      display: inline-block;
      width: 23.434524px;
      height: 23.434524px;
      transform: rotate(45deg);
      background-color: inherit;
    }
    .arrow::before {
      background-color: #fff !important;
      left: -12px;
    }
    .arrow::after {
      right: -12px;
      z-index: 3;
    }