A ball with a colour scheme already decided by the room: cherry blossom everywhere, which means pale pink is the background rather than an option.
That is more of a constraint than it first appears. Dress a princess in blossom pink and she disappears into the hall; go too far the other way and she is fighting the decoration. The gowns that work are the ones that pick up something from the room without matching it, which is the actual problem at any themed event.
Babs and Friends Back to School