Fix spaces UI in PHUIHeaderView

Summary: This should consistenly apply the styling regardless of font or size of the Header. Fixes T10485

Test Plan: Visit a Task and a Countdown in a different Space.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T10485

Differential Revision: https://secure.phabricator.com/D15374