Just to mention that I have released an update of the
writer-syntax theme, which you can find here:
I almost managed to get the option to switch between light and dark variants to work. It currently works but you have to reload twice. Any input on this would be much appreciated.
Other than that, the theme features extensive support for Markdown (with tables and CriticMarkup), JSON and YAML, and
language-todo. The font used in the screenshots is Roboto Mono.