img {
    width: 100%;
    height: 100%;
    max-height: 90vh;
    object-fit: contain;
}

.img {
    position: relative;
    display: block;
    --w: 1;
    --h: 1;
    padding-bottom: calc(100% / var(--w) * var(--h));
}
.img img {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    border: 0;
}