An OpenType font rendering (a subset of) Markdown

When writing out text in this way it is intuitive enough, and works nicely. However, when going back to make edits, it is not a fun experience.

OSes don't know quite what to do rendering cursors around the hidden markdown characters. Arrow key navigation is rough. Adding text at the beginning/end of a styled span is ambiguous whether additions should go inside/outside.

But for composing markdown separately and then displaying "rich" text in contexts that only support plain text -- this could maybe be interesting.

For adding more markdown support, headings seem like a useful and doable next feature. And tables would be a feat!