When entering fullscreen while the device is already horizontal, there are white bars on either side. However, if you enter fullscreen in portrait then rotate the device, it's not an issue.
From what I see it's due to the viewport width being set differently. The player controls when doing the latter approach are visible on the full width of the screen, whereas opening fullscreen horizontally, the controls only extend in the main box.
Additionally, the X in the corner never hides when entering horizontally.
I would like to see Orion take up the full width when horizontal, this could be linked, but that's mostly a different issue.
