Use Menlo if available.

appengine/chromium_rietveld/new_static/components/cr-diff.css

 /*
  * Copyright (c) 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.
  */
 
 :host {
     display: block;
 }
 
@@ skipping 26 matching lines @@
 
 .text,
 .row cr-action {
     padding: 0 16px;
 }
 
 .line-number,
 .text {
     white-space: pre-wrap;
     word-wrap: break-word;
-    font-family: Monaco, monospace;
+    font-family: Menlo, Monaco, monospace;
     flex-shrink: 0;
 }
 
 .line-number {
     min-width: 3em;
     text-align: right;
     color: #444;
     padding-right: 16px;
     cursor: default;
 }
@@ skipping 15 matching lines @@
     border-color: #dcdcdc;
     border-style: solid;
     border-width: 1px 0 1px 1px;
     margin-left: calc(6em + 32px);
 }
 
 .spinner {
     margin: 0.5em auto;
     display: block;
 }