nav {
      background-color: #b6b6b6;
      height: 40px;
      line-height: 40px;  
    }
    
    nav ul {
      list-style-type: none;
      display: flex;
      justify-content: flex-start; /* 靠左对齐 */
    }

    /* 标签右侧加白色分隔线 */
    nav ul li {
      width: 15%;
      text-align: center;
      box-sizing: border-box;
      position: relative;
      border-right: 2px solid white;
    }

    nav ul li a {
      color: #000;
      text-decoration: none;
      font-size: 18px;
      display: block;
    }
    
    nav ul li a:hover {
      color:#17155b;
      text-decoration: underline;
    }

    nav ul li a:focus {
      color:#17155b;
      font-weight: bold;
      text-decoration: underline;
    }
  #content {
      margin-top: 30px;
  }

  section {
      display: none;
      margin-bottom: 40px;
  }

  h3 {
      color: #17155b;
      margin-bottom: 10px;
      font-weight: bold;
  }
  img {
      max-width: 100%;
      height: auto;
  }

  .tab-content p{
      font-size: 16px;
  }
      
  .tab-content.active {
      display: block;
    }
  /*屏幕宽度较小时标签宽度均分*/
  @media(max-width:768px){
    nav ul li {
      flex: 1;
    }
  }