Remove workboard shadow, slightly nicer mobile view

Summary: Going to remove the workboard shadow area to keep the design less complex visually, shrink icons on mobile view

Test Plan: test uiexamples for new layout changes

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7516