Changing colour of the edge of the map?

Hey, I’m looking to create a mod which makes the edge of the map a different colour from the unexplored area to help with scouting, but can’t find which file to edit. If anyone could provide any pointers I’d really appreciate it.

While I’m at it, does anyone know where I’d look to adjust the scroll speed around the map to be faster than the in-game settings allow?
Thanks.

This is a really neat idea, even a line indicating where the maps stops would be nice.

Yes please! This is really annoying for me, I always misclick the edge of the map. Also does anyone know if it’s possible to make food and stone more visible and distinct on the minimap?