Docserver: there is only one.

chrome/common/extensions/docs/static/css/site.css

 /* Copyright (c) 2012 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.
  */
 
 .hidden {
   display: none;
 }
 
 body {
@@ skipping 187 matching lines @@
 
 #gc-topnav a,
 #gc-topnav button {
   background: none;
   border: none;
   color: #333;
   cursor: pointer;
   font-family: inherit;
   font-size: inherit;
   font-style: inherit;
-  font-weight: bold;
   margin: 0; padding: 0;
   outline: none;
 }
 #gc-topnav a:focus,
 #gc-topnav button:focus {
   outline: 1px dotted;
 }
 
-#branch-chooser {
+#platform-chooser {
   display: inline;
   position: relative;
-  font-weight: bold;
-}
-#branch-chooser .stable {
-  color: #0d68ae;
-}
-#branch-chooser .beta {
-  color: #409544;
-}
-#branch-chooser .dev {
-  color: #dba30d;
-}
-#branch-chooser .trunk {
-  color: #e02629;
 }
 
-#branch-chooser-popup {
+#platform-chooser-popup {
   /* Make it appear to be an extension of the header. */
   background-color: white;
   border: 1px solid #F5F5F5;
   border-top: none;
   z-index: 4;
   /* Ready to be shown by popup.js. */
   position: absolute;
   display: none;
   /* Align with the button, which have padding:6px. */
   left: -6px;
 }
 
-#branch-chooser-popup button {
+#platform-chooser-popup button {
   display: block;
   padding: 6px;
   width: 100%;
   text-align: left;
 }
-#branch-chooser-popup button:hover {
-  background-color: #F5F5F5;
+#platform-chooser-popup button:hover {
+  color: #4787ed;
 }
 
 button.google-button {
   background-color: #f5f5f5;
   border: 1px solid rgba(0,0,0,0.1);
   text-transform: uppercase;
   border-radius: 2px 0 0 0;
     -webkit-border-radius: 2px 0 0 0;
     -moz-border-radius: 2px 0 0 0;
   white-space: nowrap;
@@ skipping 333 matching lines @@
   border: 1px solid #ccc;
   margin-top: -1px;
 }
 tabs content.unselected {
   display: none;
 }
 tabs content pre {
   margin: 0;
   padding: 10px;
 }