--- a/browser/themes/shared/customizableui/customizeMode.inc.css
+++ b/browser/themes/shared/customizableui/customizeMode.inc.css
@@ -81,23 +81,16 @@
 
 #customization-done-button {
   color: #fff;
   font-weight: 700;
   border-color: #0060df;
   background-color: #0a84ff;
 }
 
-.customizationmode-button > .box-inherit {
-  border-width: 0;
-  padding: 3px 0;
-  padding-inline-start: 0;
-  padding-inline-end: 0;
-}
-
 /* We use a smaller padding to ensure images don't have padding.
  * We can't detect whether a button has an image. This button doesn't
  * so it needs more padding, so we unfortunately hardcode the extra
  * padding in here:
  */
 #customization-toolbar-visibility-button {
   padding-inline-start: 8px;
 }