Fancy launch page

We have a protocol handler, it would be good to make a https://fiddle.electronjs.org/launch/{gist_id} endpoint that will use any of the fancy techniques we know to detect if fiddle is running and launch it, if it isn't running we can give them a fancy download page with an explanation / overview of what fiddle is.

I can build that page itself and the logic but would need some help making it look nice on the website side of things 👍