It seems under Site Styles under Index Navigation I had checked "Apply Minimum Height" to All Pages. By default this sets minimum height to 50vh. I turned "Apply Minimum Height" to None. Under Custom CSS I then reduced top/bottom padding to each of the galleries blocks on each page using this code (see below). This gave me control of the white space on mobile view.
//Header Banner Padding mobile//
@media screen and (max-width:640px) {
#block-yui_3_17_2_1_1700096549547_1930{
padding-top: 0px !important;
padding-bottom: 0px !important;
}
}
//end//
