body {
            background: #b39898;
            display: grid;
            justify-content: center;
            align-items: center;
            height: 100vh;
            font-family: Arial, sans-serif;
        }
        div.header {
            text-align: center;
            margin-bottom: 20px;
            color: #f5f5f5;
        }
        .calculator {
            background: #222;
            padding: 20px;
            border-radius: 10px;
            box-shadow: 0 4px 10px rgba(0,0,0,0.2);
            width: 320px;
        }
        .display {
            background: #111;
            color: #fff;
            font-size: 2em;
            padding: 15px;
            border-radius: 5px;
            margin-bottom: 15px;
            text-align: right;
            overflow-x: auto;
        }
        .buttons {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 10px;
        }
        button {
            padding: 20px;
            font-size: 1.2em;
            border: none;
            border-radius: 5px;
            background: #333;
            color: #fff;
            cursor: pointer;
            transition: background 0.2s;
        }
        button:hover {
            background: #444;
        }
        .operator {
            background: #ff9500;
            color: #fff;
        }
        .operator:hover {
            background: #e08900;
        }
        .equal {
            background: #34c759;
            color: #fff;
            grid-column: span 2;
        }
        .equal:hover {
            background: #28a745;
        }
        .clear {
            background: #ff3b30;
            color: #fff;
        }
        .clear:hover {
            background: #c82333;
        }