Prettify frontend with a CSS template

code/app/templates/index.html

@@ -1,6 +1,8 @@
 {% extends "base.html" %}
 
 {% block content %}
+<div class="jumbotron">
 <h1 id="igdb-internation-glacier-database">IGDB: Internation Glacier Database</h1>
 <p>The IGDB is a database, that uses data from the <a href="http://dx.doi.org/10.5904/wgms-fog-2018-11">WGMS</a> to illustrate the consequences of climate change.</p>
+</div>
 {% endblock %}