Update Conpherence Main UI

Summary: Uses standard sidenav width, more spacing in labels, added background around textarea, make background work in Firefox.

Test Plan:
Test Desktop, Mobile, and Tablet break points. Test Firefox and Chrome.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11993