body {
    margin: 1;
    font-family: 'Arial', sans-serif;
    background-size: 100% 100%;
    /* display: flex; */
    align-items: center;
    justify-content: center;
    /* 将登录框放置在页面中央 */
    margin-left: 0px;
  }

  .login-form {
    margin-top: 20px;
  }

  .form-group {
    margin-bottom: 15px;
  }

  label {
    display: block;
    margin-bottom: 8px;
    color: #555;
  }

  input {
    width: 100%;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
  }

  button {
    background-color: #4caf50;
    color: #fff;
    padding: 10px 15px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
  }

  button:hover {
    background-color: #45a049;
  }

  ul {
    display: flex;
    flex-wrap: wrap;
    list-style-type: none;
  }

  li {
    flex-basis: 10%;
    /* 每个项的基础宽度为20%，即每行显示5列 */
  }

  @media (max-width: 100%) {
    li {
      flex-basis: calc(100% / 10);
      /* 计算每个项的宽度，使其在小于等于4个项时均分 */
    }
  }

  a {
    width: 180px;
    /*li元素的宽度，也就是相当于定义了一个宽度范围，当鼠标移动到上面的范围的时候就触发a:hover效果*/
    display: block;
  }

  a:hover {
    color: #0000FF;
    background: #5aaafa;
    border-radius: 7px;
  }

  /* 鼠标移动到链接上 */
  li.bc-border {
    margin-top: 3px;
  }

  .div-group {
    width: 100%;
  }

  section { 
    display: block;
    width: 100%;
    margin-bottom: 20px;
    padding: 0px;
    clear: both;
  }
  #section1 {
    background-color: #add8e6;
  }
  #section2 {
    background-color: #90ee90;
  }

  .center-ul {
    /* text-align: center; */
    list-style: none;
    padding: 0;
    margin: 0 auto;
    padding-left: 3%;
    padding-right: 2%;
  }

  .center-ul li {
    display: inline-block;
    margin: 0 10px;
  }

  .center-ul li a {
    font-size: 16px;
  }


  .mobile-center-ul {
    /* text-align: center; */
    list-style: none;
    padding: 0;
    margin: 0 auto;
    padding-left: 1%;
    padding-right: 1%;
    /* width: 150px; */
  }

  .mobile-center-ul li {
    display: inline-block;
    margin: 0 10px;
  }

  .mobile-center-ul li a {
    font-size: 15px;
    /* text-decoration: none; */
    width: 30px;
  }