body {
      font-family: Arial, sans-serif;
      margin: 0;
      padding: 0;
    }
    
    header {
      background-color: #4287f5;
      color: white;
      padding: 20px;
      text-align: center;
    }
    
    nav {
      background-color: #f2f2f2;
      padding: 10px;
      text-align: center;
    }
    
    nav a {
      color: black;
      margin: 0 10px;
      text-decoration: none;
    }
    
    main {
      margin: 20px;
    }
    
    footer {
      background-color: #333;
      color: white;
      padding: 10px;
      text-align: center;
    }
    
    /* 登录页和注册页的样式 */
    .form-container {
        max-width: 400px;
        margin: 0 auto;
    }

    .form-container h2 {
        text-align: center;
    }

    .form-container form  {
        display: flex;
        flex-direction: column;
        padding: 20px;
        background-color: #f2f2f2;
        border-radius: 5px;
    }

    .form-container form input {
        margin-bottom: 10px;
        padding: 10px;