index.html.erb in reveal-ck-3.6.0

- old
+ new

@@ -1,7 +1,7 @@
 <!doctype html>
 <html lang="en">
-  <head>
+  <head prefix="<%= head_prefix %>">
     <%= head %>
   </head>
 
   <body>
     <%= body(slides_html) %>