MD Settings: Fix main content position and sizing to match spec.

chrome/browser/resources/settings/basic_page/basic_page.html

 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://md-settings/appearance_page/appearance_page.html">
 <link rel="import" href="chrome://md-settings/search_page/search_page.html">
 <link rel="import" href="chrome://md-settings/settings_page/settings_page_visibility.html">
 <link rel="import" href="chrome://md-settings/settings_page/settings_section.html">
 <link rel="import" href="chrome://md-settings/on_startup_page/on_startup_page.html">
 <link rel="import" href="chrome://md-settings/people_page/people_page.html">
 <link rel="import" href="chrome://md-settings/reset_page/reset_profile_banner.html">
 
 <if expr="chromeos">
 <link rel="import" href="chrome://md-settings/internet_page/internet_page.html">
 </if>
 
 <if expr="not chromeos">
 <link rel="import" href="chrome://md-settings/default_browser_page/default_browser_page.html">
 </if>
 
 <dom-module id="settings-basic-page">
-  <link rel="import" type="css" href="basic_page.css">
+  <link rel="import" type="css" href="chrome://md-settings/settings_page.css">
   <template>
     <template is="dom-if" if="[[showResetProfileBanner_]]">
       <settings-reset-profile-banner on-reset-done="onResetDone_">
       </settings-reset-profile-banner>
     </template>
     <template is="dom-if" if="[[showPage(pageVisibility.people)]]" restamp>
       <settings-section page-title="[[i18n('peoplePageTitle')]]"
           current-route="[[currentRoute]]" section="people">
         <settings-people-page prefs="{{prefs}}" current-route="{{currentRoute}}">
         </settings-people-page>
@@ skipping 38 matching lines @@
           expand-container="{{expandContainer}}"
           current-route="[[currentRoute]]" section="defaultBrowser">
         <settings-default-browser-page>
         </settings-default-browser-page>
       </settings-section>
     </template>
 </if>
   </template>
   <script src="basic_page.js"></script>
 </dom-module>