Thanks. That's a nice idea... but if it's that simple I might as well just use a static markdown to html converter, if I don't need the support for diagram generation (which admittedly looks like a killer feature). For example, pandoc supports that (or latex -> html or pretty much anything else), and the results are similar, e.g. (in this case, specifying a very small amount of additional css): http://pandoc.org/demo/example3.html

I'm currently using couscous (http://couscous.io/) to convert markdown to html but it's far more work to use, and does a whole bunch more than that, such as twig templates, so I'll consider switching to markdeep or pandoc.