[Theme: twentyfourteen] page content being hidden on mobile devices?

In regards to this ticket here: https://core.trac.wordpress.org/ticket/27031

Has anybody come up with a solution? The theme is hiding my bbpress forum and mobile devices, or any screen smaller than 400px.

if you drag the corner of the browser to make the window smaller, you will see the page content eventually gets hidden.
here is my website, thanks! http://motocrossnw.net/forum/