Theme 404 page

templates/404.html

@@ -1,3 +1,10 @@
-<h1>Page not found</h1>
+{% extends "base.html" %}
 
-<h2>Sorry, this page could not be found.</h2>
+{% block content %}
+  <header id="index-header" class="d-flex align-items-center">
+    <div class="text-center m-auto text-light">
+      <h1 class="display-1">There's nothing here!</h1>
+      <p class="lead">The page you were looking for could not be found</p>
+    </div>
+  </header>
+{% endblock %}