* {
    box-sizing: border-box;
}

body {
    margin: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    background: linear-gradient(135deg, #e899b7, #a77c8e);
    font-family: Arial, sans-serif;
}


#calculator {
    width: 360px;
    background: #3d1f2d;
    border-radius: 28px;
    padding: 22px;
    box-shadow:
        0 20px 40px rgba(61, 31, 45, 0.35),
        inset 0 1px 1px rgba(255, 255, 255, 0.08);
}

/* Display */
#display {
    width: 100%;
    height: 90px;
    padding: 20px;
    margin-bottom: 18px;

    background: #27151e;
    border: none;
    border-radius: 18px;

    color: #fff;
    font-size: 2.5rem;
    font-weight: bold;
    text-align: right;

    outline: none;
    box-shadow: inset 0 4px 10px rgba(0, 0, 0, 0.25);
}


#keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}


button {
    height: 65px;
    border: none;
    border-radius: 18px;

    font-family: Arial, sans-serif;
    font-size: 1.3rem;
    font-weight: bold;

    color: #3d1f2d;
    background: #f3b3c9;

    cursor: pointer;
    transition: 
        transform 0.15s ease,
        background-color 0.15s ease,
        box-shadow 0.15s ease;

    box-shadow: 0 5px 10px rgba(0, 0, 0, 0.15);
}

button:hover {
    background: #ffc8da;
    transform: translateY(-2px);
    box-shadow: 0 8px 15px rgba(0, 0, 0, 0.2);
}


button:active {
    transform: translateY(2px);
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.2);
}


.operator-btn {
    background: #c96a98;
    color: white;
}

.operator-btn:hover {
    background: #df82af;
}

/* Equals button */
button:nth-last-child(2) {
    background: #9e4673;
    color: white;
}

button:nth-last-child(2):hover {
    background: #b95785;
}


button:last-child {
    background: #71304f;
    color: white;
}

button:last-child:hover {
    background: #8d3d63;
}