This looks pretty cool, but why do you need to "run" delta rather than having it dump out the static HTML? I'd love to use this as server-less review: "Oh, I've got this local diff on my box, here look at this HTML for a prettified view".
Good idea! There's already a way to print out html to the command line, but it should really be the same as what gets rendered in the browser. I've added a Github issue to track. this.