.calculator {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 10px;
        }

        .calculator button {
            padding: 15px;
            font-size: 16px;
            border: none;
            border-radius: 4px;
            background-color: #29a0b1;
            /*background-color: #003060;*/
            color: white;
            cursor: pointer;
        }

        .calculator button:hover {
            background-color: #0056b3;
        }

        .display {
            grid-column: span 4;
            padding: 10px;
            font-size: 18px;
            border: 1px solid #ccc;
            border-radius: 4px;
            text-align: right;
        }
        .button-zero {
            grid-column: span 2;
        }