Hey, sorry to hear you had a bad experience. I'm guessing you're also affected by the Firefox bug reported below?
As for full screening, the individual elements are not designed to change their proportions. However, using the browser's zoom feature should work as intended.
It's a game jam, not every trade-off can be optimal, and I apologize for the bug. Unfortunately I can't submit patches before the jam ends, but resetting the save has helped for some people. Using Chrome is also an option.