Fix height of the viewer-pane in Material Design PDF Viewer

chrome/browser/resources/pdf/elements/viewer-pane/viewer-pane.css

 /* Copyright 2015 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. */
 
 :host /deep/ paper-dialog {
   background-color: rgb(66, 66, 66);
   color: rgb(250, 250, 250);
   /* Since the pane slides in from the right, we want the scrollbar to be on
    * the left. Setting direction to rtl achieves this.
    */
   direction: rtl;
   font-family: Roboto, 'Helvetica Neue', Helvetica, Arial;
-  height: calc(100% - 64px);
+  height: calc(100% - 56px);
   margin: 0;
   right: 0;
-  top: 64px;
+  top: 56px;
   width: 22em;
 }
 
 #reset-content {
   direction: ltr;
 }
 
 :host /deep/ #scroller > h1 {
   direction: ltr;
   font-family: Roboto, 'Helvetica Neue', Helvetica, Arial;
 }
 
 hr {
   background: rgb(66, 66, 66);
   border: 0;
   border-bottom: 1px dashed rgb(250, 250, 250);
 }