remove extra whitespace making the messages view disappear in Firefox

slackviewer/templates/viewer.html

@@ -58,7 +58,7 @@ <h3 id="mpim-title">Group Direct Messages</h3>
             {% endfor %}
         </ul>
     </div>
-    {% endif %}
+    {%- endif -%}
     <div class="messages">
         {% for message in messages %}
             {% if message.msg or message.files %}