MD User Manager: latest design change, css refactoring, accessiblity, and bug fixes

chrome/browser/resources/md_user_manager/supervised_user_learn_more.html

 <link rel="import" href="chrome://md-user-manager/shared_styles.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/iron-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 
 <dom-module id="supervised-user-learn-more">
   <template>
     <style include="shared-styles">
       :host {
         align-self: center;
       }
 
       #container {
-        color: var(--paper-grey-800);
+        color: var(--main-text-color);
         line-height: 20px;
         width: 624px;
       }
 
       #title-area {
         border-bottom: 1px solid rgba(0, 0, 0, .12);
         font-size: 16px;
         padding-bottom: 16px;
       }
 
       #title-area iron-icon {
         --iron-icon-height: 20px;
         --iron-icon-width: 20px;
-        color: var(--google-grey-500);
+        color: var(--title-icon-color);
       }
 
       .content-area {
         padding-top: 32px;
         white-space: pre-wrap;
         word-wrap: break-word;
       }
 
       #actions {
         bottom: 16px;
         position: absolute;
         right: 16px;
       }
 
       :host-context([dir='rtl']) #actions {
         left: 16px;
         right: auto;
       }
-
-      #actions paper-button {
-        border-radius: 2px;
-        font-weight: 500;
-        line-height: 32px;
-        margin: 0;
-        min-width: 52px;
-        padding: 0 16px;
-      }
-
-      #actions #done {
-        background: var(--google-blue-500);
-        color: white;
-      }
     </style>
     <div id="container">
       <div id="title-area" class="horizontal justified layout">
-        <span id="title" i18n-content="supervisedUserLearnMoreTitle"></span>
+        <span id="title">$i18n{supervisedUserLearnMoreTitle}</span>
         <iron-icon icon="supervisor-account"></iron-icon>
       </div>
       <div class="content-area"
           i18n-values=".innerHTML:supervisedUserLearnMoreText">
       </div>
       <div id="actions">
-        <paper-button id="done" on-tap="onDoneTap_"
-            i18n-content="supervisedUserLearnMoreDone">
+        <paper-button id="done" class="action primary" on-tap="onDoneTap_">
+          $i18n{supervisedUserLearnMoreDone}
         </paper-button>
       </div>
     </div>
   </template>
   <script src="chrome://md-user-manager/supervised_user_learn_more.js"></script>
 </dom-module>