Add option to switch text/background colors to black/white for better readability

[Arg4f]

Hey there!

I'm finding hard to keep reading for long periods because of the contrast white text on dark background. This is a common readability issue related to lots of people.

It would be great to make it more accessible for everyone by adding an option to change the colors for text and background to black and white.
Even better, would be colors like dark gray for text and dull white for background.

I love the work you did so far! And I hope it would keep improving to help everyone :)
Cheers