Good point -- I had some CSS attached to H1 nodes that accidentally also matched H1s in the editor. Should be fixed now.

Also note, some of the tooltips appear as "undefined" and there's no way to advance the cursor past a horizontal rule at the end of the document.

What do you mean by tooltips?

There's a solution in the works for the latter problem.

The tooltips that appear when hovering over toolbar items. The ones that are dropdowns, 'Insert' and 'Type' show up as undefined.