body {
      background: linear-gradient(to bottom, #74ebd5, #9face6);
      text-align: center;
      padding: 20px;
    }
    .container {
      background: #fff;
      border-radius: 15px;
      box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
      padding: 30px;
      max-width: 500px;
      margin: auto;
    }
    h1 {
      font-size: 2rem;
      color: #333;
      margin-bottom: 10px;
    }
    p {
      color: #666;
    }
    .btn {
      margin-top: 10px;
    }
    #output {
      margin-top: 20px;
      font-weight: bold;
    }