That was writing. As for the
– that’s all a matter of stylesheets and CSS, since markdown is rendered as HTML. DEVONthink actually gives you more control here than many. The possibilities are practically endless.
If you’ve never heard of CSS, it might seem daunting. But the basics are pretty easy, and @chrillek has written a nice beginners’ guide here: CSS for Markdown, the basics
You can also try searching the forum; some users have shared their stylesheets for others to download.