Approach, after discussion – 

(These only show the interior of the page, not the universal header or footer) 

Only "Browse" and "Recent Submissions"  (or other content list, such as Featured Items or Most Downloaded, etc) are in the desktop view sidebar

Search is not shown ; it should stay in the universal header for all pages, in the same place

News should go in the main section, not the sidebar, since it should be very flexible for admins to add whatever HTML they need to

Edit Community Page Responsive Behavior (editable mockups)