Last Github commit on 2017. See https://github.com/n457/Uncolored
Our users have written 1 comments and reviews about (Un)colored, and it has gotten 17 likes
It's pretty light, free and open source, it has the basics for what you'd normally use it, you can save documents as markdown or html and it looks nice. Go for it.
Took one star out because the settings panel is too rudimentary to be useful at this point.