{% load cms_tags %}

<div class="panel-heading
    {% if instance.classes %} {{ instance.classes }}{% endif %}"
    {{ instance.attributes_str }}>

    {% if instance.title %}
        <h3 class="panel-title">{{ instance.title }}</h3>
    {% endif %}

    {% for plugin in instance.child_plugin_instances %}
        {% render_plugin plugin %}
    {% endfor %}
</div>
