R1:413c65b60862

Fix margin hover issue on pinboard.

Summary: Removes the -1px and tweaks the colors just a bit more.

Test Plan: Review Pholio and Macro.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2664

Differential Revision: https://secure.phabricator.com/D5213