Pre-HTML5 it was pretty much a cardinal rule that a page should only have a single h1 element. Post HTML5 you can have multiple ones but they should be semantically arranged to show their meaning.
I notice that Wikidata prints two h1's in the page in the same element. It hides the first one which is created automatically by Vector.
I suspect this is very bad for SEO and also rather hacky. I've seen the same problem in the Flow extension - the Flow team wanted to restyle the header but MediaWiki code didn't allow it - it's not malleable enough.
Let's make headings more configurable to avoid this. Maybe this is a method on the Title class or a simple template that can be configured in LocalSettings.php
It seems Wikidata needs to simply override the printable title so instead of saying "Q1" the heading says "Universe (Q1)". How can we support this better skin-experts?