Use a split toggle button to reflect scaling state.

remoting/webapp/me2mom/choice.css

 /* Copyright (c) 2011 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.
  */
 
 /* Elements */
 a {
   color: rgb(0, 102, 204);
   text-decoration: none;
 }
@@ skipping 22 matching lines @@
   -webkit-user-select: none;
 }
 
 button:hover {
   background: #ebebeb -webkit-linear-gradient(#fefefe, #f8f8f8 40%, #e9e9e9);
   border-color: #999;
   color: #222;
   -webkit-box-shadow: 0px 1px 3px rgba(0, 0, 0, 0.2);
 }
 
-button:active {
+button:active, .toggle-button-active, .toggle-button-active:hover {
   background: #ebebeb -webkit-linear-gradient(#f4f4f4, #efefef 40%, #dcdcdc);
   color: #333;
   -webkit-box-shadow: inset 0px 1px 3px rgba(0, 0, 0, 0.2);
 }
 
 button[disabled], .button[disabled]:hover {
   background: -webkit-linear-gradient(#fafafa, #f4f4f4 40%, #e5e5e5);
   border-color: #aaa;
   color: #888;
   -webkit-box-shadow: none;
@@ skipping 170 matching lines @@
   margin: 100px auto 0 auto;
   padding: 10px;
   width: 640px;
 }
 
 #session-mode {
   width: 100%;
   -webkit-user-select: none;
 }
 
-#session-status-msg {
-  /*
-    clear: both; forces the session-controls div to size appropriately for
-    session-buttons.
-  */
-  clear: both;
-  font-family: monospace;
-  font-size: small;
-  margin: 5px;
+#toggle-scaling {
+  margin: 1px 0 0 0;
+  padding: 1px;
+  min-width: 0;
+  line-height: 0;
 }
-
-#server-response {
-  font-weight: bolder;
-}