Set max width on error page and include Last login on error page

- Updated error_base template so that it contained the Root Vue component, which was the reason that the last login was not previously displaying
- Deleted unused css
- Created css variable max-page-width for use on the error page, topbar, and other full width elements

templates/error.html

@@ -5,6 +5,7 @@
 {% block content %}
 
 <main class="usa-section usa-content error-page">
+  <div class="panel">
     <div class="panel__heading">
       {{ Icon('cloud', classes="icon--red icon--large")}}
       <hr>
@@ -17,6 +18,7 @@
         {%- endif %}
       </p>
     </div>
+  </div>
 </main>
 
 {% endblock %}