The ‘H’ button turns the paragraph into an h1 node. It does not work properly inside code blocks, because the code highlighter’s styles override it. I should probably disable it inside code blocks.
My Firefox (86.0, Ubuntu) does nothing if you type ‘/’ or ‘’’, but I’ve added preventdefaults to the html just in case.
Correction: the reason my Firefox does not open the quick search box is that I’ve disabled it in the settings. Preventdefaults don’t help here. Darn.
Re publishing it as a package: I have a nagging fear that it’s not production-ready (for example, I’m not sure how serious the performance issued I mentioned above are), but the plan is to turn it into a package sooner or later.