Clean up some tablet issues with new nav layouts

Summary: Makes sidenav disappear again on projects/profiles, but shows it on home again (tablet views).

Test Plan: Visit Profile/Projects/Home on mobile, desktop, and tablet. See nav disappear correctly.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D16369