MD WebUI: Networking polish in OOBE and Settings

chrome/browser/resources/chromeos/login/oobe_nav_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. */
 
 #button {
   --paper-button-flat-keyboard-focus: {
     border-color: rgba(66, 133, 244, 0.4); /* #4284f4 */
     border-radius: 2px;
     border-style: solid;
     border-width: 2px;
   };
   color: var(--google-blue-500);
   font: var(--oobe-roboto-bold), sans-serif;
   font-size: 12px;
   height: 32px; /* = 28 + border (2px + 2px) */
   margin: 0;
   min-width: 92px; /* = 88 + border (2px + 2px) */
-  padding: 0;
+  padding: 0 16px;
 }
 
 #button:not([focused]) {
   border-color: transparent;
   border-radius: 2px;
   border-style: solid;
   border-width: 2px;
 }
 
 #text {
-  -webkit-padding-end: 16px;
   text-transform: none;
 }
 
 iron-icon {
   --iron-icon-height: 12px;
   --iron-icon-width: 12px;
-  -webkit-padding-end: 8px;
-  -webkit-padding-start: 16px;
+  padding: 0 8px;
 }
 
 #button[disabled] #text,
 #button[disabled] iron-icon {
   color: rgba(0, 0, 0, 0.34);
 }
 
+paper-button[disabled] {
+  background: transparent;
+}