Center the focus of the text input in magnifier screen.

chrome/browser/resources/options/browser_options.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. */
 
 #change-home-page-section {
   margin-left: 30px;
 }
 
 #home-page-url {
   display: inline-block;
@@ skipping 460 matching lines @@
 #accessibility-autoclick .controlled-setting-with-label {
   -webkit-box-align: baseline;
 }
 
 #accessibility-autoclick-dropdown,
 #accessibility-autoclick-label {
   /* Same as .controlled-setting-with-label > input + span. */
   -webkit-margin-start: 0.6em;
 }
 
+#accessibility-screen-magnifier-center-focus-check {
+  -webkit-margin-start: 0.4em;
+}
+
 #battery-icon {
   display: inline-block;
   height: 25px;
   vertical-align: middle;
   width: 25px;
 }
 
 div[guestmode=true] :-webkit-any(
 <if expr="not chromeos">
     #searchBox,
@@ skipping 16 matching lines @@
 
 #about-button {
   -webkit-margin-end: 30px;
 }
 
 /* An input that has no function except to take up the same amount of space as
  * a checkbox. */
 .spacer-checkbox {
   visibility: hidden;
 }