Embedded Extension Options: Change header border from shadow to line

chrome/browser/resources/extensions/extension_options_overlay.css

 /* Copyright 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. */
 
 #extension-options-overlay {
   overflow: hidden;
 }
 
 #extension-options-overlay-header {
   align-items: center;
-  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.26);
+  border-bottom: solid lightgray 1px;
   display: flex;
   position: relative;
 }
 
 #extension-options-overlay-icon {
   padding: 8px;
 }
 
 #extension-options-overlay-icon {
   height: 32px;
   width: 32px;
 }
 
 #extension-options-overlay-title {
   /* Cancel left padding to line up with the icon. */
   padding-left: 0;
 }