diff --git a/browser/themes/windows/browser.css b/browser/themes/windows/browser.css
index 9487e4e7af0..c615175dd1f 100644
--- a/browser/themes/windows/browser.css
+++ b/browser/themes/windows/browser.css
@@ -2500,10 +2500,6 @@ chatbox {
 
 %include ../shared/customizableui/customizeMode.inc.css
 
-#main-window:-moz-any([customize-entering],[customize-exiting]) label {
-  transform: perspective(1px);
-}
-
 #main-window[customize-entered] {
   background-image: url("chrome://browser/skin/customizableui/customizeMode-gridTexture.png");
   background-attachment: fixed;