app/views/classified_advertisement/tasks/_navigation.html.erb
<ul class="nav nav-pills">
<li role="presentation" class="<%= current_page?(story_tasks_path(@story)) ? 'active' : '' %>">
<%= link_to t('general.list'), story_tasks_path(@story) %>
</li>
<li role="presentation" class="<%= current_page?(calendar_story_tasks_path(@story)) ? 'active' : '' %>">
<%= link_to t('general.calendar'), calendar_story_tasks_path(@story) %>
</li>
</ul>