Clean up Oblivious skin

Summary: Adds Remarkup rules and CSS, cleans up some spacing a color. Ref T9546

Test Plan: Review a blog post list, and a blog

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9546

Differential Revision: https://secure.phabricator.com/D14421