body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f4f4f4;
    font-family: Arial, sans-serif;
}

.keypad {
    display: grid;
    grid-template-columns: repeat(3, 80px);
    gap: 15px;
}

.keypad button {
    width: 80px;
    height: 80px;
    border: none;
    border-radius: 10px;
    background-color: #007bff;
    color: white;
    font-size: 24px;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: background-color 0.2s;
}

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

.keypad button:active {
    background-color: #004091;
}

.display {
    grid-column: span 3;
    height: 50px;
    border: 2px solid #007bff;
    border-radius: 10px;
    text-align: center;
    font-size: 24px;
    line-height: 50px;
    margin-bottom: 15px;
    background-color: white;
}