{% set class_prev = "btn btn-default" if newer_activities_url else "btn disabled" %}
{% set class_next = "btn btn-default" if older_activities_url else "btn disabled" %}

<div id="activity_page_buttons" class="activity_buttons" style="margin-top: 25px;">
  <a href="{{ newer_activities_url }}" class="{{ class_prev }}">{{ _('Newer activities') }}</a>
  <a href="{{ older_activities_url }}" class="{{ class_next }}">{{ _('Older activities') }}</a>
</div>