<div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">

{% for section in site.data.tutorials %}

<div class="panel panel-default">

<div class="panel-heading">

<h4 class="panel-title">

<a role="button" data-toggle="collapse" data-parent="#accordion" href="#collapse-{{forloop.index}}" aria-expanded="false" aria-controls="collapse-{{forloop.index}}">

{{ section.title }}

</a>

</h4>

</div>

<div id="collapse-{{forloop.index}}" class="panel-collapse collapse" role="tabpanel" aria-labelledby="headingOne">

<ul class="list-group">

{% for item in section.tutorials %}

{% assign item_url = item | prepend:"/tutorials/" | append:"/" %}

{% assign p = site.tutorials | where:"url", item_url | first %}

<a class="list-group-item {% if item_url == page.url %}active{% endif %}" href="{{ p.url | prepend: site.baseurl }}">{{ p.title }}</a>

{% endfor %}

</ul>

</div>

</div>

{% endfor %}