#gallery {
    width: 100%;
    height: 250px;
    background-color: #111;
    position: relative;
}

#gallery button {
    position: absolute;
    top: calc(50% - 15px);
    border-radius: 100px;
    width: 30px;
    height: 30px;
    background-color: #4448;
}
#gallery button:hover {
    background-color: #6668;
}
#gallery button:active {
    background-color: #3338;
}

#gallery #prev {
    left: -50px;
    transition: left 100ms;
}
#gallery:hover #prev {
    left: 20px;
}
#gallery #next {
    right: -50px;
    transition: right 100ms;
}
#gallery:hover #next {
    right: 20px;
}

#gallery img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: contain;
}
#gallery img#oldImage {
    display: none;
}