The navigation HUD at the bottom of my Trello page just got HUGE! It was just fine an hour ago, but now all the buttons look like this:

What did I click and how do I make it go back to the small icons again??? I've been searching shortcuts and the message board, but I can't find anything about it.
I'm opted in to the Beta right now. It hasn't been forced on me yet, but others at my company have it so I switched early to get used to it.