Yeah, I just built an [internal] CSS documentation system; every item has a fully editable example using CSS in style tags on the page, each with contenteditable applied to allow users to play around with it; editing within the style tag immediately alters the styling of the associated example. Works beautifully, as I have no need to persist anything, and zero JS used. (I get this is an edge case; I've tried using it a couple of times for persisted input and, yeah, not a good idea past simple I/O)