fix PR #535

Use the "empty_element" CSS class.

searx/templates/simple/result_templates/videos.html

@@ -10,7 +10,7 @@
     {{ result.content|safe }}
   </p>
 {%- else %}
-  <p class="content italic_font">
+  <p class="content empty_element">
     {{ _('This site did not provide any description.')|safe }}
   </p>
 {% endif -%}