Some styling + draft 404 page

templates/bundles/TwigBundle/Exception/error404.html.twig

@@ -0,0 +1,9 @@
+{% extends 'base.html.twig' %}
+
+{% block title %}404 - Not Found | ArCOA{% endblock %}
+
+{% block body %}
+
+<h1 class="is-size-1 has-text-centered">404 - Not Found</h1>
+
+{% endblock %}