Following a conversation on twitter (https://twitter.com/patrickkettner/status/316722610463461376), I added support for intrinsic widths. Currently there are only prefixed implementations on desktop Firefox and desktop Chrome.
Added support for intrinsic widths
Thanks! I'm doing a little more testing on this one, but it should appear on the site soon.
No problem, if there is anything at all I can do to help with testing, let me know.