Add Workboard UI Color to sidenav, fix fullscreen CSS

Summary: Uses the background color changes to show also on the side nav. Places color on entire body so fullscreen doesn't show other body color.

Test Plan: Review various workboard colors at normal and fullscreen

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D15283