Hahaha, I really liked the soundtrack!
It was a really fun experience. I never saw such an inverted snake game before!
I have a few small remarks:
sometimes the salt is not picked up while the snake is in it. You have to be perfectly in the center to pick it up.
Sometimes food will spawn exactly on salt.
It could also be fun to spawn the food a certain distance directly in front of the snake, instead of randomly in the field. This way the player can plan his route less in advance and is forced to have a more active playstyle. I would probably do a combination of this and the random spawning.
Overall a great game, great job!