Don't know if you're the same person that reported this on Discord, but if not/if other people read this:
The game has a minimum default height. Normally it's low enough that it's not an issue, but if your screen is low enough resolution then it'd probably show like that. I should be able to reduce the minimum height further, just never had a reason/need to do so. And I'll also make escape open the options menu so you can swap to windowed mode.