div.imgGroup {
     text-align: center;
     margin: 0em;
}

/* video is 1280 x 720 px, i.e.: 80em x 45em */
div.imgGroup video {
     width:     100%;
     margin:    0em;
}

div.imgGroup img {
     width:   100%;
     margin:  0em;
}

/* upright / portrait / 778px = 48.625em */
img.up {
     max-width: 48.625em;
}

/* crosswise / landscape / 1037px = 64.8125em */
img.cr {
     max-width: 64.8125em;
}

/* upright / portrait */
video.up {
     max-width: 35em;
}

/* crosswise / landscape */
video.cr {
     max-width: 80em;
}