[fix] fix no_results.html template of the simple theme

searx/templates/simple/messages/no_results.html

+{% from 'simple/macros.html' import icon %}
 {% if unresponsive_engines %}
-<div class="alert alert-danger fade in" role="alert">
-    <p><strong>{{ _('Error!') }}</strong> {{ _('Engines cannot retrieve results.') }}</p>
-    <p>
-        {% for engine_name, error_type in unresponsive_engines %}
-        {{ engine_name }} ({{ error_type }}){% if not loop.last %}, {% endif %}
-        {% endfor %}
-    </p>
-    <p><small>{{ _('Please, try again later or find another searx instance.') }}</small></p>
+<div class="dialog-error" role="alert">
+  <p><strong>{{ _('Error!') }}</strong> {{ _('Engines cannot retrieve results.') }}</p>
+  <p>
+    {% for engine_name, error_type in unresponsive_engines %}
+    {{ engine_name }} ({{ error_type }}){% if not loop.last %}, {% endif %}
+    {% endfor %}
+  </p>
+  <p><small>{{ _('Please, try again later or find another searx instance.') }}</small></p>
 </div>
 {% else %}
-<div class="alert alert-info fade in" role="alert">
-    <strong>{{ _('Sorry!') }}</strong>
-    {{ _('we didn\'t find any results. Please use another query or search in more categories.') }}
+<div class="dialog-error" role="alert">
+  <p><strong>{{ _('Sorry!') }}</strong></p>
+  <p>{{ _('we didn\'t find any results. Please use another query or search in more categories.') }}</p>
 </div>
 {% endif %}