Use Menlo if available.

appengine/chromium_rietveld/new_static/components/common.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; }
 
 h1, h2 {
     padding: 0;
@@ skipping 61 matching lines @@
 }
 
 textarea,
 input[type=text] {
     display: block;
     background-color: white;
     border-radius: 1px;
     border: 1px solid rgba(0, 0, 0, 0.15);
     border-top: 1px solid rgba(0, 0, 0, 0.25);
     box-sizing: border-box;
-    font-family: Monaco, monospace;
+    font-family: Menlo, Monaco, monospace;
     font-size: 1em;
     margin: 0;
     width: 100%;
 }
 
 textarea:hover,
 input[type=text]:hover {
   border: 1px solid #b9b9b9;
   border-top-color: #a0a0a0;
 }
 
 textarea:focus,
 input[type=text]:focus {
     border: 1px solid #4d90fe;
     outline: none;
 }
 
 input.invalid,
 textarea.invalid {
     border: 1px solid #DD4B39;
 }