Add QR code for wifi on index page, some responsive design fixes

app/templates/usb-file-viewer.html

@@ -1,13 +1,15 @@
 {% extends "base.html" %}
 
 {% block content %}
+    <h1 class="title is-large butter-title">{{ _('File Viewer') }}</h1>
+
 <div>
-<table class="table">
+<table class="table" style="margin: 0 auto">
   <thead>
     <tr>
        <th></th>
       <th>File Name</th>
-      <th>Date modified</th>
+      <th class="file-viewer-date-modified">Date modified</th>
         <th>Download</th>
     </tr>
   </thead>
@@ -23,7 +25,7 @@
         <td>{{ f.name}}</td>
         {% endif %}
 
-        <td>{{ f.last_modified}}</td>
+        <td class="file-viewer-date-modified">{{ f.last_modified}}</td>
           {% if f.is_file %}
            <td><a href="{{ url_for('serve_file', filepath=f.path) }}">Download</a></td>
           {% endif %}