Pholio CSS touchups for inline comments.

Summary: Tightened up spaces, made inline area more 'inset', tweaked colors to match timeline view.

Test Plan: Tested mocks with and without inline comments.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5188