body {
      font-family: Arial, sans-serif;
      padding: 2rem;
      background-color: #f0f2f5;
    }
    .register-container {
      max-width: 400px;
      margin: auto;
      padding: 2rem;
      background: white;
      box-shadow: 0 0 10px rgba(0,0,0,0.1);
      border-radius: 8px;
    }
    input, button {
      width: 100%;
      padding: 0.8rem;
      margin-top: 1rem;
      font-size: 1rem;
    }
    .error {
      color: red;
      margin-top: 1rem;
    }