R1:1711e516e4ee

Use more common styles for setup issue CSS

Summary: Updates setup CSS to use more common colors, spacing.

Test Plan: review a fatal, a common error, and uiexample

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8006