.content {
    width: 380px!important;
    margin: auto!important;
    background-color: hsl(0, 0%, 50%);
    justify-content: center;
    display: block;
    align-items: center;
}

#calculator {
    font-family: Arial, Helvetica, sans-serif;
    background-color: hsl(0, 0%, 15%);
    border-radius: 15px;
    max-width: 380px;
    overflow: hidden;
}

#display {
    width: 380px;
    padding: 20px;
    font-size: 5rem;
    text-align: left;
    border: none;
    background-color: hsl(0, 0%, 20%);
    color: white;
}

#keys {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    padding: 10px;
    width: 380px;
}

button {
    width: 75px;
    height: 75px;
    border-radius: 50px;
    border: none;
    background-color: hsl(0, 0%, 30%);
    color: white;
    font-size: 3rem;
    font-weight: bold;
    cursor: pointer;
}

button:hover {
    background-color: hsl(0, 0%, 40%)
}

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

.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%, 5%);
}