display last 5 presentations by default on project pages (#2527)

Author: davidlange6

_includes/list_project_presentations.html

@@ -1,12 +1,13 @@
 {% assign pres_list = site.data['sorted_presentations'] | where_exp: "pres", "pres.project contains include.shortname" %}
 
 {% if pres_list.size > 0 %}
-<h3>Presentations</h3>
-<ul>
-{% for talk in pres_list %}
-  <li>
-    {%- include print_pres.html talk=talk -%}
-  </li>
-{% endfor %}
-</ul>
+<section class="">
+  <div class="container-lg p-responsive py-5 py-md-6 ">
+    <h3 id="presentations" class="alt-h2 text-center mb-3 mt-lg-6" id="pres">Presentations</h3>
+    {% expandable pres_list 5 %}
+      {% include print_pres.html talk=expandable %}
+    {% endexpandable %}
+</div>
+</section>
 {% endif %}
+