Made a super simple vanilla JS/HTML5 markdown editor/viewer recently, just wanted the basics and especially to be able to hit CTRL-P and print the resulting HTML nicely or save to a PDF.
This supports MathJax, and automatically saves to local storage so you can use it as a notes app or quickly pick up where you left off. Hope you also find it useful!
I think this is nice. Simple and to the point. Well done.
However, I can't help but think that I have a fairly wide monitor and that I would find it nicer to have editing and viewing views side by side instead of having to toggle between them.
I didn't get around to that because my monitor is not amazingly wide (mainly using a laptop :P). Thanks for the feedback though, I may add that in the future.