diff --git a/docs/source/_static/custom.css b/docs/source/_static/custom.css
index 6764e04e..80660072 100644
--- a/docs/source/_static/custom.css
+++ b/docs/source/_static/custom.css
@@ -1,3 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
 .toggle {
     display: block;
     clear: both;