Fix layout to include category titles and links to category pages.

_sass/_layout.scss

@@ -172,7 +172,8 @@
 }
 
 .page-heading {
-    font-size: 20px;
+    font-size: 22px;
+    text-decoration: underline;
 }
 
 .post-list {

index.html

@@ -4,8 +4,10 @@ layout: default
 <div class="home">
   {% for category in site.categories %}
     {% if category.first == "meta" %} {% continue %} {% endif %}
-    <h1 class="page-heading">{{ site.config.category_titles[category] }}</h1>
     <div class="column col-{{site.categories.size | minus: 1}}">
+      <a href="{{category.first | prepend: site.baseurl}}">
+        <h1 class="page-heading">{{ site.category_titles[category.first] }}</h1>
+      </a>
       {% include category_list.html category=category.first limit=5 %}
     </div>
   {% endfor %}