I do something similar in a bookmarklet to give myself a nice looking notepad. It's essentially a padded content editable div, with a prepopulated H1. This lets me print it out or save it as a document when needed. Which is never.
That's one of my favorite "stupid HTML tricks". I wonder who first figured it out? I can't find the original blog post (if it even was) and now it's a known thing:
