.calculator {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: 10px;
    max-width: 300px;
    margin: 0 auto;
    padding: 20px;
    border: 1px solid #ccc;
    border-radius: 5px;
    box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.2);
}

.display {
    grid-column: span 4;
    text-align: right;
    font-size: 24px;
    padding: 10px;
    background-color: #f5f5f5;
    border: 1px solid #ccc;
    border-radius: 3px;
}

.operator, .digit {
    font-size: 18px;
    padding: 10px;
    text-align: center;
    border: 1px solid #ccc;
    border-radius: 3px;
    cursor: pointer;
}

#clear, #calculate {
    grid-column: span 2;
}