Add the correct class for the post date.

Author: johno

_layouts/post.html

@@ -3,7 +3,7 @@
 ---
 <div class="post-header mb2">
   <h1 class="py2">{{ page.title }}</h1>
-  <span class="meta">{{ page.date | date: "%b %-d, %Y" }}</span>
+  <span class="post-meta">{{ page.date | date: "%b %-d, %Y" }}</span>
 </div>
 
 <article class="post-content">