body {
      font-family: Arial, sans-serif;
      margin: 0;
      padding: 0;
      background-color: #f4f4f4;
  }
  header {
      background: #333;
      color: white;
      padding: 20px;
      text-align: center;
  }
  nav {
      background: #444;
      padding: 10px;
      text-align: center;
  }
  nav a {
      color: white;
      text-decoration: none;
      padding: 10px 20px;
      display: inline-block;
  }
  nav a:hover {
      background: #555;
  }
  .container {
      max-width: 800px;
      margin: 50px auto;
      background: white;
      padding: 40px;
      border-radius: 10px;
      box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  }
  .container h1 {
    text-align: center;
  }
  h1 {
      color: #333;
      font-size: 2.5em;
  }