diff --git a/browser/themes/linux/customizableui/panelUIOverlay.css b/browser/themes/linux/customizableui/panelUIOverlay.css
index f82125007c11..e5531db7f202 100644
--- a/browser/themes/linux/customizableui/panelUIOverlay.css
+++ b/browser/themes/linux/customizableui/panelUIOverlay.css
@@ -45,10 +45,6 @@
   -moz-padding-start: 0;
 }
 
-.subviewbutton.bookmark-item > .toolbarbutton-icon {
-  -moz-margin-start: 3px;
-}
-
 /* subviewbutton entries for social sidebars have images that come from external
 /* sources, and are not guaranteed to be the size we want, so force the size on
 /* those icons. */
diff --git a/browser/themes/windows/customizableui/panelUIOverlay.css b/browser/themes/windows/customizableui/panelUIOverlay.css
index 31d428117e80..6fbbfeb9fda1 100644
--- a/browser/themes/windows/customizableui/panelUIOverlay.css
+++ b/browser/themes/windows/customizableui/panelUIOverlay.css
@@ -100,10 +100,6 @@ menuitem[type="checkbox"].subviewbutton {
   -moz-padding-start: 0;
 }
 
-.subviewbutton.bookmark-item > .toolbarbutton-icon {
-  -moz-margin-start: 3px;
-}
-
 /* subviewbutton entries for social sidebars have images that come from external
 /* sources, and are not guaranteed to be the size we want, so force the size on
 /* those icons. */