Add missing navigation style.

Change-Id: I62c00206a02b40a54b6ab9ac95d44c98865e051d
diff --git a/_includes/header404.html b/_includes/header404.html
index 8c851d7..64c3b32 100644
--- a/_includes/header404.html
+++ b/_includes/header404.html
@@ -1,5 +1,15 @@
 <header>
 <div class="wrapper">
+    <a class="site-title" href="{{ site.baseurl }}/">{{ site.title }}</a>
+
+    <nav class="site-nav">
+      <a href="#" class="menu-icon">
+        <svg viewBox="0 0 18 15">
+          <path fill="#424242" d="M18,1.484c0,0.82-0.665,1.484-1.484,1.484H1.484C0.665,2.969,0,2.304,0,1.484l0,0C0,0.665,0.665,0,1.484,0 h15.031C17.335,0,18,0.665,18,1.484L18,1.484z"/>
+          <path fill="#424242" d="M18,7.516C18,8.335,17.335,9,16.516,9H1.484C0.665,9,0,8.335,0,7.516l0,0c0-0.82,0.665-1.484,1.484-1.484 h15.031C17.335,6.031,18,6.696,18,7.516L18,7.516z"/>
+          <path fill="#424242" d="M18,13.516C18,14.335,17.335,15,16.516,15H1.484C0.665,15,0,14.335,0,13.516l0,0 c0-0.82,0.665-1.484,1.484-1.484h15.031C17.335,12.031,18,12.696,18,13.516L18,13.516z"/>
+        </svg>
+      </a>
 
       <div class="trigger">
         {% for page in site.pages %}