Font Settings API: UI overhaul of example extension.

chrome/common/extensions/docs/examples/api/fontSettings/css/overlay.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. */
 
 /* The shield that overlays the background. */
 .overlay {
   -webkit-box-align: center;
   -webkit-box-orient: vertical;
   -webkit-box-pack: center;
   -webkit-transition: 200ms opacity;
@@ skipping 52 matching lines @@
 }
 
 .overlay .page.pulse {
   -webkit-animation-duration: 180ms;
   -webkit-animation-iteration-count: 1;
   -webkit-animation-name: pulse;
   -webkit-animation-timing-function: ease-in-out;
 }
 
 .overlay .page > .close-button {
-  background-image: url('chrome://theme/IDR_WEB_UI_CLOSE');
+  background-image: url('../images/x.png');
   background-position: center;
   background-repeat: no-repeat;
   height: 14px;
   position: absolute;
   right: 7px;
   top: 7px;
   width: 14px;
 }
 
 html[dir='rtl'] .overlay .page > .close-button {
   left: 10px;
   right: auto;
 }
 
 .overlay .page > .close-button:hover {
-  background-image: url('chrome://theme/IDR_WEB_UI_CLOSE_HOVER');
+  background-image: url('../images/x-hover.png');
 }
 
 .overlay .page > .close-button:active {
-  background-image: url('chrome://theme/IDR_WEB_UI_CLOSE_PRESSED');
+  background-image: url('../images/x-pressed.png');
 }
 
 .overlay .page h1 {
   -webkit-padding-end: 24px;
   -webkit-user-select: none;
   color: #333;
   /* 120% of the body's font-size of 84% is 16px. This will keep the relative
    * size between the body and these titles consistent. */
   font-size: 120%;
   /* TODO(flackr): Pages like sync-setup and delete user collapse the margin
@@ skipping 50 matching lines @@
 .overlay .page .content-area::-webkit-scrollbar-thumb {
   background-color: rgba(0, 0, 0, 0.2);
   border: 2px solid white;
   border-radius: 8px;
 }
 
 .overlay .page .content-area::-webkit-scrollbar-thumb:hover {
   background-color: rgba(0, 0, 0, 0.5);
 }
 </if>