Center empty message on webiscite (#239)

Author: mfosterw

democrasite/templates/webiscite/bill_list.html

@@ -43,7 +43,9 @@ <h5 class="card-title">{{ bill }}</h5>
       </div>
       {% if forloop.counter|divisibleby:4 or forloop.last %}</div>{% endif %}
   {% empty %}
-    {{ empty_message }}
+    <div class="text-center">
+      <h5 class="mb-1">{{ empty_message }}</h5>
+    </div>
   {% endfor %}
 {% endblock content %}