body {
      font-family: Arial, sans-serif;
      background: linear-gradient(darkblue, grey);
      color: #ffffff;
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      margin: 0;
    }

    .calculator {
      background: #ffffff;
      padding: 20px 25px;
      border-radius: 12px;
      box-shadow: 0 6px 18px rgba(0,0,0,0.1);
      width: 320px;
      text-align: center;
    }

    h2 {
      margin-bottom: 15px;
      color: #333;
    }

    input[type="number"] {
      width: 80%;
      padding: 8px;
      margin: 6px 0;
      border-radius: 8px;
      border: 1px solid #ccc;
      font-size: 16px;
      text-align: center;
    }

    .buttons {
      margin-top: 10px;
      display: flex;
      justify-content: center;
      gap: 10px;
    }

    button {
      padding: 8px 14px;
      border: none;
      border-radius: 6px;
      background-color: #2563eb;
      color: white;
      font-size: 16px;
      cursor: pointer;
      transition: background 0.3s;
    }

    button:hover {
      background-color: #1d4ed8;
    }

    #hasil {
      margin-top: 20px;
      font-size: 18px;
      font-weight: bold;
      color: #333;
    }