diff --git a/_includes/top.html b/_includes/top.html
index 5ae7ded..642507c 100644
--- a/_includes/top.html
+++ b/_includes/top.html
@@ -6,7 +6,7 @@
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <title>{{ page.title }}</title>
-    <link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
+    <link rel="stylesheet" href="https://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
     <link rel="stylesheet" href="{{ site.url }}/css/main.css">
 
     <!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->