Misc Diffusion/Differential CSS tweaks

Summary: Various tweaks and fixes. Adds a File Contents view in Diffusion, normalizes spaces, colors.

Test Plan: tested differential and diffusion in my sandbox.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T3952

Differential Revision: https://secure.phabricator.com/D7325

src/applications/diffusion/controller/DiffusionBrowseFileController.php

@@ -297,11 +297,14 @@ final class DiffusionBrowseFileController extends DiffusionBrowseController {
       $corpus = phutil_tag(
         'div',
         array(
-          'style' => 'padding: 0 2em;',
           'id' => $id,
         ),
         $corpus_table);
 
+      $corpus = id(new PHUIObjectBoxView())
+        ->setHeaderText('File Contents')
+        ->appendChild($corpus);
+
       Javelin::initBehavior('load-blame', array('id' => $id));
     }