This is pretty nice! It's not always obvious how much engineering it takes to make an app like this that's powerful enough to be useful for daily work without the UX getting in the way.

I think this is the closest I've seen anyone come to solving the problem of having separate "write" and "read" modes for Markdown editing in a web browser without resorting to a split-screen view. It's not _perfect_ (likely due to codemirror limitations) but what's there is pretty well-executed.

I might have to borrow a couple ideas from this for my own effort at a personal knowledge base: https://github.com/cu/silicon