ChromeOS OOBE: Fix OK button on Welcome screen.

chrome/browser/resources/chromeos/login/oobe_text_button.css

 /* Copyright 2016 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. */
 
-#textButton {
-  --paper-button-flat-keyboard-focus: {
-    border-color: rgba(66, 133, 244, 0.4); /* #4284f4 */
-    border-radius: 2px;
-    border-style: solid;
-    border-width: 2px;
-  };
+paper-button {
+  border-color: var(--oobe-text-button-border-color, transparent);
+  border-radius: 2px;
+  border-style: solid;
+  border-width: 2px;
   height: 32px; /* = 28px + 2 * 2px border */
   margin: 0;
   padding: 0;
 }
 
-#textButton:not([focused]) {
-  border-color: var(--oobe-text-button-border-color, transparent);
-  border-radius: 2px;
-  border-style: solid;
-  border-width: 2px;
+paper-button[focused] {
+  border-color: var(--oobe-text-button-focused-border-color);
 }
 
 #container {
   border-radius: 2px;
   padding: 0 16px;
 }
 
 #textButton:not([inverse]):not([disabled]) #container {
   background-color: white
   color: var(--google-blue-500);
 }
 
 #textButton[inverse]:not([disabled]) #container {
   background-color: var(--google-blue-500);
   color: white;
 }
 
 ::content * {
   font: var(--oobe-roboto-medium), sans-serif;
   font-size: 12px;
   text-transform: none;
 }