[MD settings] css for row separator

chrome/browser/resources/settings/appearance_page/appearance_page.html

 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/md_select_css.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="appearance_browser_proxy.html">
 <link rel="import" href="../controls/controlled_radio_button.html">
 <link rel="import" href="../controls/extension_controlled_indicator.html">
@@ skipping 56 matching lines @@
               <div class="secondary" id="themesSecondary">
                 [[themeSublabel_]]
               </div>
             </div>
             <button class="icon-external" is="paper-icon-button-light"
                 aria-label="$i18n{themes}"
                 aria-describedby="themesSecondary"></button>
           </div>
 <if expr="not is_linux or chromeos">
           <template is="dom-if" if="[[prefs.extensions.theme.id.value]]">
-            <div class="secondary-action">
-              <paper-button id="useDefault" on-tap="onUseDefaultTap_"
-                  class="secondary-button">
-                $i18n{resetToDefaultTheme}
-              </paper-button>
-            </div>
+            <div class="separator"></div>
+            <paper-button id="useDefault" on-tap="onUseDefaultTap_"
+                class="secondary-button">
+              $i18n{resetToDefaultTheme}
+            </paper-button>
           </template>
 </if>
 <if expr="is_linux and not chromeos">
-          <div class="secondary-action" hidden="[[!showThemesSecondary_(
-            prefs.extensions.theme.id.value, useSystemTheme_)]]">
+          <div class="layout horizontal center" hidden="[[!showThemesSecondary_(
+              prefs.extensions.theme.id.value, useSystemTheme_)]]"
+              id="themesSecondarActions">

[Dan Beam, 2017/05/01 15:32:31]

secondary

[dschuyler, 2017/05/01 19:26:11]

Done.

+            <div class="separator"></div>
             <template is="dom-if" if="[[showUseClassic_(
                 prefs.extensions.theme.id.value, useSystemTheme_)]]" restamp>
               <paper-button id="useDefault" on-tap="onUseDefaultTap_"
                   class="secondary-button">
                 $i18n{useClassicTheme}
               </paper-button>
             </template>
             <template is="dom-if" if="[[showUseSystem_(
                 prefs.extensions.theme.id.value, useSystemTheme_)]]" restamp>
               <paper-button id="useSystem" on-tap="onUseSystemTap_"
@@ skipping 96 matching lines @@
             associated-control="[[$$('#customize-fonts-subpage-trigger')]]"
             page-title="$i18n{customizeFonts}">
           <settings-appearance-fonts-page prefs="{{prefs}}">
           </settings-appearance-fonts-page>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="appearance_page.js"></script>
 </dom-module>