diff --git a/_includes/header.html b/_includes/header.html
index 091ef18..20c01bb 100644
--- a/_includes/header.html
+++ b/_includes/header.html
@@ -1,4 +1,4 @@
-      <div id="header">
+      <div id="header" class="wrapper">
 	<div id="title" class="topnav">
 	  <a href="{{ site.url }}">{{ site.title | default: site.github.repository_name }}</a>
 	  {% for my_page in site.pages %}