Add a black outline to the tower exits (top of tower)

When I am on the top of a tower, I always look around for the exit so I get to the view, everything being the same colour and having no doors makes it sometimes confusing, especially when playing on Windowed Mode or Low Screen brightness. A black outline around that hole or a red line on the bottom would make it much easier.
I know it’s a petty complaint but I sometimes spend an embarassing amount of time finding out how to leave the room.