Use localization files in templates.

themes/vanilla/layouts/blog/single.html

@@ -6,14 +6,14 @@
         <a class="button" href="{{ $.Site.BaseURL }}/tags/{{ . | urlize }}">{{ . }}</a>
         {{ end }}
     </p>
-    <p>Posted on {{ .Date.Format "January 2, 2006" }}.</p>
+    <p>{{ i18n "PostedOn" . }}</p>
 </div>
 
 <div class="post-content">
     {{ if not (eq .TableOfContents "<nav id=\"TableOfContents\"></nav>") }}
     <div class="table-of-contents">
         <div class="wrapper">
-            <em>Table of Contents</em>
+            <em>{{ i18n "TableOfContents" }}</em>
             {{ .TableOfContents }}
         </div>
     </div>