Neat. Along the same lines for emacs people, there's writemode-good (https://github.com/bnbeckwith/writegood-mode), and for Sublime Text there's Writing Style (https://sublime.wbond.net/packages/Writing%20Style).

Also, heads up that the site layout is not responsive: viewing at ~800px width places buttons all over the left side of the screen in an ugly way.