body {
    font-family: sans-serif;
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f0f8ff;
    text-align: center;
  }
  h1 {
    color: #333;
    margin-top: 50px;
  }
  #result {
    font-size: 60px;
    margin: 40px 0;
    color: #d32f2f;
    min-height: 80px;
  }
  button {
    font-size: 20px;
    padding: 15px 40px;
    background-color: #4CAF50;
    color: white;
    border: none;
    border-radius: 30px;
    cursor: pointer;
    transition: transform 0.1s;
  }
  button:active {
    transform: scale(0.95);
  }
  button:disabled {
    background-color: #ccc;
    cursor: wait;
  }