[uber page] Lighten horizontal line below developer buttons

chrome/browser/resources/extensions/extensions.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. */
 
 html.loading * {
   -webkit-transition-duration: 0 !important;
 }
 
 /* Developer mode */
 
 #dev-controls {
   -webkit-padding-end: 3px;
   -webkit-padding-start: 4px;
   -webkit-transition: padding 100ms, height 100ms, opacity 100ms;
-  border-bottom: 1px solid rgb(205, 205, 205);
+  border-bottom: 1px solid #eee;
   display: -webkit-box;
   height: 0;
   opacity: 0;
   overflow: hidden;
 }
 
 #extension-settings.dev-mode #dev-controls {
   -webkit-transition-duration: 250ms;
   height: 32px;
   opacity: 1;
@@ skipping 150 matching lines @@
   vertical-align: middle;
 }
 
 .extension-list-item:not(:hover) .trash:not(:focus) {
   opacity: 0;
 }
 
 .extension-list-item-wrapper.may-not-disable .trash {
   visibility: hidden;
 }