diff --git a/docs/assets/css/extra.css b/docs/assets/css/extra.css
index 04b92b5cf1..6f6d314eaa 100644
--- a/docs/assets/css/extra.css
+++ b/docs/assets/css/extra.css
@@ -1,3 +1,6 @@
 nav.md-nav.md-nav--secondary > ul ul {
   display: none;
 }
+nav.md-nav.md-nav--secondary > ul ul ul {
+  display: none;
+}