[MD settings] separator line for side nav

chrome/browser/resources/settings/settings_menu/settings_menu.html

 <link rel="import" href="chrome://resources/cr_elements/cr_icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/av-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/device-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/hardware-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/image-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/iron-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/social-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-menu.html">
@@ skipping 15 matching lines @@
       .iron-selected:not(.menu-trigger) > iron-icon {
         fill: var(--google-blue-500);
       }
 
       .menu-trigger span {
         -webkit-margin-end: 16px;
         flex: 1;
       }
 
       paper-menu {
-        background: none;  /* Overrides <paper-menu> default. */
-        color: var(--settings-nav-grey);
-        font-size: 13px;
         --paper-menu-selected-item: {
           font-weight: 500;
         };
         --paper-menu-focused-item-after: {
           background: none;
         };
+        background: none;  /* Overrides <paper-menu> default. */
+        color: var(--settings-nav-grey);
+        font-size: 13px;
+        padding: 0;
+      }
+
+      paper-submenu > div {
+        margin-top: 8px;
       }
 
       paper-submenu {
         --paper-menu-selected-item: {
           font-weight: 500;
         };
       }
 
       paper-submenu paper-menu {
         --paper-menu-selected-item: {
           color: var(--google-blue-500);
           font-weight: 500;
         };
-        padding: 0;
       }
 
       paper-submenu div {
         @apply(--layout-center);
         -webkit-margin-start: 24px;
         display: flex;
         font-size: 13px;
         font-weight: 500;
         min-height: 40px;
       }
+
+      .separator {
+        /* Per Alan@, this line is different from the other separator lines. */
+        border-bottom: 1px solid rgba(0, 0, 0, 0.08);
+        margin-top: 8px;
+      }
     </style>
     <paper-menu name="root-menu">
       <paper-submenu data-page="basic" id="basicPage" opened="{{basicOpened_}}">
         <div class="menu-trigger" data-section="" on-tap="openPage_">
           <span i18n-content="basicPageTitle"></span>
           <iron-icon icon="[[arrowState_(basicOpened_)]]" item-icon></iron-icon>
         </div>
         <paper-menu attr-for-selected="data-section" class="menu-content"
             data-page="basic" id="basicMenu">
 <if expr="chromeos">
@@ skipping 78 matching lines @@
             <iron-icon icon="icons:build" item-icon></iron-icon>
             <span i18n-content="systemPageTitle"></span>
           </div>
 </if>
           <div data-section="reset" on-tap="openPage_">
             <iron-icon icon="icons:restore" item-icon></iron-icon>
             <span i18n-content="resetPageTitle"></span>
           </div>
         </paper-menu>
       </paper-submenu>
+      <div class="separator"></div>
       <paper-submenu data-page="about">
         <div class="menu-trigger" on-tap="openPage_" data-section="">
           <span i18n-content="aboutPageTitle"></span>
         </div>
       </paper-submenu>
     </paper-menu>
   </template>
   <script src="settings_menu.js"></script>
 </dom-module>