Contrast variation tweak

[gummyWalrus]

Hey there, :wave:

I've been using this since a little week and I like it, it was about time that someone created an alternative to gnome 'Piss yellow' bedtime mode :crescent_moon:, thank you guys !

Some of the color schemes are a bit hard to read for me, and that's why the color intensity tweak is really cool ! To go along with that, I think it would be a good idea to add a 'Contrast' setting if possible. I think it will improve great time the shades possibilities.

Thanks for your time ! :kissing_heart: