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

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

/* upright / portrait / 389 px = 24.3125em */
img.up {
     max-width: 24.3125em;
}

/* crosswise / landscape / 518 px = 32.375em */
img.cr {
     max-width: 32.375em;
}