#center-sticky {
    display: table;
    border: 2px solid;
    background-color: whitesmoke;
    position: fixed;
    inset: 0px;
    width: 12rem;
    height: 12rem;
    max-width: 100vw;
    max-height: 100dvh;
    margin: auto;
    z-index: 99;
}
span {
    text-align: center;
    display: table-cell;
    vertical-align: middle;
}
#photos img {
    width: 100vw;
    max-width: 100vw;
}