It's not just the contents; it's the tag itself. The only thing that is special to my knowledge is that the HTML 5 parser understands it and applies the correct

It's not just the contents; it's the tag itself. The only thing that is special to my knowledge is that the HTML 5 parser understands it and applies the correct XML namespace. ... Ah, but thinking about it while I type these lines tells me where I'm wrong: It is an HTML element that's by default rendered as a block element, takes part in all the typical layout stuff. I can apply border, border-radius, background, etc. to it and it behaves like a div. Just that I can also put graphics inside.