body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(135deg, #4e54c8, #8f94fb);
    font-family: Arial, sans-serif;
}

.container {
    display: flex;
    justify-content: center;
}

.calculator {
    background-color: rgba(255, 255, 255, 0.9);
    border-radius: 10px;
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.3);
    padding: 20px;
    max-width: 400px;
    width: 100%;
}

#display {
    width: 100%;
    height: 40px;
    font-size: 24px;
    text-align: right;
    margin-bottom: 10px;
    padding: 5px;
    border: 1px solid #ccc;
    border-radius: 5px;
    background-color: #f0f0f0;
}

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

.button {
    background-color: #c9d342dd;
    color: white;
    text-align: center;
    padding: 20px;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.2s;
    font-size: 20px;
}

.button:hover {
    background-color: #ff6b81;
    transform: scale(1.05);
}

@media (max-width: 400px) {
    .button {
        padding: 15px;
        font-size: 18px;
    }

    #display {
        font-size: 20px;
    }
}