body {
    font-family: Arial, sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background-color: #f5f5f5;
  }
  /* 默认亮色模式 */
body {
    background-color: #ffffff;
    color: #000000;
    transition: background-color 0.3s, color 0.3s;
  }
  
  /* 暗色模式 */
  body.dark-mode {
    background-color: #121212;
    color: #ffffff;
  }
  
  /* 切换按钮样式 */
  #themeToggle {
    position: fixed;
    top: 10px;
    right: 10px;
    padding: 10px;
    background-color: #007bff;
    color: #ffffff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
  }
  
  #themeToggle:hover {
    background-color: #0056b3;
  }

  input {
    padding: 10px;
    margin: 5px 0;
    width: 250px;
    border: 1px solid #ddd;
    border-radius: 4px;
  }

  button {
    padding: 10px 15px;
    border: none;
    border-radius: 4px;
    background-color: #28a745;
    color: white;
    cursor: pointer;
    margin: 10px 0;
  }

  button:hover {
    background-color: #218838;
  }

  #otpDisplay {
    margin-top: 15px;
    font-size: 24px;
    font-weight: bold;
  }