Dark and Light Colour Schemes for Renpy

The code adds a button in the Preferences screen that lets the user switch between Dark and Light colour schemes. There's a tutorial within this project to explain how to add the code to your own game and then tweak the colours and UI. 

It works best with a new project, and is a bit janky. I was only going to write a tutorial but it was easier to just create a project with all the code and a little bit of explanation.