Off-topic, but I _love_ the "sidenote" format for footnotes. I've been meaning to implement that in my own blog for a while, now. I'll check out the source for inspiration.
I enable the sidenotes based on how “wide” your current viewport is. I’ve just personally found they don’t work as well on smaller screens.
I wrote it with simple jQuery. Happy to share if anyone is interested and don’t want to have to write it from scratch.