#imgDiv {
    display: flex;
    align-items: center;
    justify-content: center;

    height: 400px;
}

#img {
    height: 300px;
    width: 300px;
}

#imgDiv > button {
    height: 40px;
    width: 40px;

    font-size: 20px;
    text-align: center;

    border-radius: 50%;

    background-color: black;
}