body {
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    background: linear-gradient(135deg, #fc806a, #90acda);
}

.calculator {
    font-family: Arial, sans-serif;
    background-color: hsl(0, 0%, 15%);
    border-radius: 15px;
    max-width: 500px;
    overflow: hidden;
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.2);
}

#display {
    width: 100%;
    padding: 15px;
    font-size: 2.5rem;
    border: none;
    background-color: hsl(0, 0%, 20%);
    color: white;
    text-align: right;
    border-bottom: 2px solid hsl(0, 0%, 30%);
    outline: none; /* Removes the blue border on focus */
    box-sizing: border-box; /* Ensures padding doesn’t overflow */
}

#keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    padding: 25px;
}

button {
    width: 75px;
    height: 75px;
    border-radius: 50px;
    border: none;
    background-color: hsl(0, 0%, 30%);
    color: white;
    font-size: 2rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
}

button:hover {
    background-color: hsl(0, 0%, 40%);
    transform: scale(1.05);
}

button:active {
    background-color: hsl(0, 0%, 50%);
    transform: scale(1);
}

.operator-btn {
    background-color: hsl(35, 100%, 55%);
}

.operator-btn:hover {
    background-color: hsl(35, 100%, 65%);
}

.operator-btn:active {
    background-color: hsl(35, 100%, 75%);
}

@media (max-width: 768px) {
    #display {
        font-size: 1.8rem;
        padding: 8px;
    }

    #keys {
        gap: 8px;
    }

    button {
        font-size: 1.2rem;
        width: 50px;
        height: 50px;
        border-radius: 50px; /* Smaller font size for buttons */
    }
}

/* Media query for very small screens (phones in portrait mode) */
@media (max-width: 480px) {
    #display {
        font-size: 1.5rem;
        padding: 5px;
    }

    button {
        font-size: 1rem; /* Even smaller text for compact view */
    }
}