diff --git a/toolkit/themes/gnomestripe/global/notification.css b/toolkit/themes/gnomestripe/global/notification.css
index 90e056baa5e0..b8ed5d92e11f 100644
--- a/toolkit/themes/gnomestripe/global/notification.css
+++ b/toolkit/themes/gnomestripe/global/notification.css
@@ -32,3 +32,7 @@ notification[type="critical"] {
 .messageCloseButton {
   list-style-image: url("moz-icon://stock/gtk-close?size=menu");
 }
+
+.messageCloseButton > .toolbarbutton-icon {
+  margin: 0px !important;
+}