.calculator {
    width: 320px;
    margin: 50px auto;
    border-radius: 8px;
    padding: 20px;
    background-color: #fff; /* White background */
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

#display {
    width: calc(100% - 20px);
    margin-bottom: 15px;
    padding: 12px;
    font-size: 22px;
    text-align: right;
    border: 1px solid #ddd; /* Lighter border */
    border-radius: 5px;
}

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

button {
    padding: 12px;
    font-size: 18px;
    border: none;
    border-radius: 5px;
    background-color: #f0f0f0; /* Light gray buttons */
    cursor: pointer;
    transition: background-color 0.2s ease;
}

button:hover {
    background-color: #e0e0e0;
}

button:active {
    background-color: #ccc;
}