Make the horizontal rule between project entries responsive.

Author: jdblischak

layouts/projects/summary.html

@@ -26,4 +26,8 @@ <h5 class="subtitle is-5">{{ .Params.account }}</h5>
     </div>
   </div>
 </article>
-<hr/>
+<div class="columns is-centered">
+  <div class="column is-four-fifths">
+    <hr/>
+  </div>
+</div>