R1:9618ab642643

Use more standard colors in remarkup errors

Summary: These should all be shades now instead of pure colors.

Test Plan: Fake an error, see correct muted color.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D13580