How to change the colour of the blinds

[NitroVicky]

I would like to change the colour of the dark blinds that cover unexplored area:

This darkness looks very sinister and I am a bit demotivated to go into it

I was wondering if it's possible to tweak some lines of the source code or edit a file so that the unexplored area is covered by a more inviting colour, e.g. green, or some pattern to decorate the edge of the known world?

I want to do this just for myself, locally. I'm not asking for anything official to be implemented as I think the dark blinds are good for some maps' themes.