Plex Media Player looks like web page. How to fix?

I did something weird tonight while watching Plex. I’m not sure what I did, but all of a sudden, Plex Media server changed from looking like a full screen media player into the screens I see when I open Plex in my browser. How do I get it back?

It went from having a largish row of icons at the top of the screen to looking just like the browser screen looks when I click Open Plex… in the OS X menu bar.

You have switched to windowed mode. Put it back to full screen & it will look as previously.

I believe it’s still full screen. I’ll post a screenshot when I get back in front of it.