Ask HN: library to produce nice-looking installers for web apps?

I'm talking about the "add to home screen" prompt you get with some installable web apps under iOS.

Ideally, the prompt would also explain how to add the web app as a bookmark in Android.

I've got one that I've written, but I'm not entirely happy with the way that it looks.

Also, I'd really like to see something that's themable via CSS so it matches the rest of the app.

If there's nothing good out there, I'll work on mine some more and put it on github.

Edit: I'm using jQuery Mobile for the project I'm working on now, but independence of the underlying framework would also be great.