.container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    background-color: #f0f0f0;
    font-family: 'Arial', sans-serif;
}

.container h2 {
    font-size: 3rem;
    color: #333;
}

.container .cal-frame {
    width: 400px;
    height: 500px;
    background-color: #e6e6e6;
    border-radius: 20px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 20px;
}

.cal-frame .display {
    width: 70%;
    height: 50px;
    background-color: #fff;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: 20px;
    text-align: right;
    font-size: 2rem;
    color: #333;
}

.cal-btn {
    margin-top: 4px;
    display: grid;
    place-content: center;
    grid-template-columns: repeat(4, 60px);
    gap: 10px;
}

button {
    width: 60px;
    height: 60px;
    background-color: #fff;
    border: none;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
    font-size: 25px;
    cursor: pointer;
}

button:hover {
    background-color: #eee;
    transform: scale(1.1);
    transition: .3s ease;
}

.operator {
    color: #ff7200;
}

@media (max-width: 786px) {
    .container .cal-frame {
        width: 80%;
        height: 60vh;
    }
    .container h2 {
        font-size: 1.6rem;
    }

    .cal-frame .display {
        width: 70%;
        height: 40px;
        font-size: 1.5rem;
    }

    .cal-btn {
        grid-template-columns: repeat(4, 1fr);
    }

    button {
        width: 100%;
        height: 50px;
        font-size: 20px;
    }

    .display {
        width: 90%;
        height: 40px;
        font-size: 1.5rem;
    }
}