When I play the game in fullscreen, it has a bright blue letterbox border on top and bottom. It's pretty distracting as opposed to a black letterbox. Is there any way to fix this?

recently got a Steam Deck and noticed nothing was there, I was hoping this could be added.

Game is closing soon as I press Play in steam

Enjoying the game so far, but has anyone found the times for the time trials to be massively erratic? - sometimes I can complete a level completely smoothly and be twenty seconds off gold pace - sometimes I can make mistakes and make gold comfortably - I just had a run of 4-2, made a few blunders, and still finished over a minute under gold pace...

...no keyboard remapping. For some reason i still dont know, game devs still think 2D games are better played with a controller.