Bring consistency to templates, update structure to use new base

alchemy/templates/categories.html

@@ -1,14 +1,17 @@
 {% extends "base.html" %}
 
 {% block title %}
-  {{ SITENAME }} — Categories
+Categories {{ super() }}
+{% endblock %}
+
+{% block page_header %}
+Categories
 {% endblock %}
 
 {% block content %}
-  <h1>Categories on {{ SITENAME }}</h1>
-  <ul class="list-unstyled">
-    {% for category, articles in categories %}
-      <li><a href="{{ SITEURL }}/{{ category.url }}">{{ category }}</a></li>
-    {% endfor %}
-  </ul>
+<ul class="list-unstyled">
+  {% for category, articles in categories %}
+  <li><a href="{{ SITEURL }}/{{ category.url }}">{{ category }}</a></li>
+  {% endfor %}
+</ul>
 {% endblock %}