Show WP Touch Mobile vs Desktop Info in Gravity Forms Notification?

I’m working on a website that’s using Gravity Forms and WP Touch Pro.

The client would like the form notifications to tell him whether the user was viewing the mobile version of the site or the desktop version.

I can use the {user_agent} merge field to include the browser and platform information, which will tell him if the form was submitted from a mobile device, but the results there are identical whether the user is using the mobile version or has opted for the desktop version on the mobile device.

Unless I’m mistaken, the only back-end difference between those two versions is which stylesheet is being used, the one for the site’s regular theme, or the one for the WP Touch theme.

1 – Am I right about that, or is there some other difference that I could exploit to get this info passed via the form? Where’s the code that’s deciding which stylesheet to use? Can I slip in a definition of a hidden field there?

2 – Assuming that is right, is there any way to define the value of a hidden field via the CSS? I’m afraid I know the answer to that one, because if there were, I’m pretty sure Google would’ve told me about it.