Hi Brian,
In DIV mode tables can be horizontal (what you are used to) and vertical (when the screen space gets too narrow.)
Of course there are settings you can choose, and things you can do to optimize the experience for both approaches.
Perhaps that would be a good question for Tursday.
But in principle, based on your screen-shot, I would say it's gone to vertical mode because the space is narrow?
cheers
Bruce