Using HTML5, in Orchard CMS mobile application

I was just reading the guidelines and trying to get my head around the apparent contradiction in http://www.orchardproject.net/docs/UI-guidelines-for-theme-authors.ashx

On one hand, it says: "Orchard assumes the use of HTML5... it is a strong recommendation. "

On the other hand it also says: "Your web pages should work even if JavaScript is disabled in the browser"

How can the HTML5 tags possible work w/o JavaScript - which they have recommended as a solution? Since I'm doing a mobile application, should I totally ignore HTML5 tags then as the safest approach for browser compatibility in mobile?

Update: Anyone had a look at Twitter's new mobile site in HTML5? Is it using HTML5 tags and just focusing on modern smart phones?

I'm afraid you'll have to be a little more specific about the problems you are anticipating, in particular as compared to the same thing done without HTML 5. It's not clear to me whether this is a comment about Orchard or about HTML 5. Another thing to keep in mind is that while we recommend HTML 5, you can perfectly well replace all the markup into whatever dialect you prefer to use.

Ended up using a different wrapper for the widgets that does have to depend on the generic wrapper for widgets which has pre-configured HTML5 tags like <header />.