One minor critique... the example placeholders are of the form "example.com" but it seems to reject domains that are not fully qualified (e.g. "http://example.com)
Thx. Really, without the http:// - darn - do you have an example, that would be awesome if you did. I just tried a few and they seem to work. But clearly there’s a bug somewhere so I’d love to squash it!
I think it's because you've specified the type attribute of the input box as URL. Certain newer browsers will force validation on that (latest chrome and ff both do).