diff --git a/index.html b/index.html
index aca8b5e..d015c58 100644
--- a/index.html
+++ b/index.html
@@ -12,7 +12,8 @@
     <title>SNU ACM Chapter</title>
 
     <!-- Bootstrap Core CSS -->
-    <link rel="stylesheet" href="https://bootswatch.com/flatly/bootstrap.min.css" type="text/css">
+    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css"
+        integrity="sha384-1q8mTJOASx8j1Au+a5WDVnPi2lkFfwwEAa8hDDdjZlpLegxhjVME1fgjWPGmkzs7" crossorigin="anonymous">
 
     <!-- Custom Fonts -->
     <link href='http://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800' rel='stylesheet' type='text/css'>