Add a max width to distilled pages

components/dom_distiller/core/css/distilledpage.css

 /* Copyright 2014 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 /* Set the global 'box-sizing' state to 'border-box'.
  * *::after and *::before used to select psuedo-elements not selectable by *. */
 
 *,
 *::after,
 *::before {
@@ skipping 129 matching lines @@
 #showOriginal {
   margin: auto 1.296rem 1.296rem 1.296rem;
 }
 
 #content {
   margin-top: 1.296rem;
 }
 
 /* Main margins. */
 
+body {
+  max-width: 800px;
+  margin: 0px auto;
+}
+
 #mainContent {
   margin: 1.296rem 1.296rem auto;
 }
 
 /* Link colors for light, dark and sepia themes */
 
 a:link {
   color: #55F;
 }
 
@@ skipping 90 matching lines @@
 
 pre {
   line-height: 1.296rem;
   overflow-x: scroll;
   padding: .5em;
 }
 
 .hidden {
   display: none;
 }