diff --git a/gtk-3.0/gtk.css b/gtk-3.0/gtk.css
index 24e0537..1643aed 100644
--- a/gtk-3.0/gtk.css
+++ b/gtk-3.0/gtk.css
@@ -933,6 +933,8 @@ notebook {
 	background-color: transparent;
 }
 
+notebook.frame {border: none;}
+
 /* gtk-3.12 */
 notebook,
 notebook > header {
diff --git a/gtk-4.0/gtk.css b/gtk-4.0/gtk.css
index 259fc0f..48b22e8 100644
--- a/gtk-4.0/gtk.css
+++ b/gtk-4.0/gtk.css
@@ -980,6 +980,8 @@ notebook {
 	background-color: transparent;
 }
 
+notebook.frame {border: none;}
+
 /* gtk-3.12 */
 notebook,
 notebook > header {