diff --git a/toolkit/themes/shared/popupnotification.inc.css b/toolkit/themes/shared/popupnotification.inc.css
index 89695ac460dd..0999a4ad3de4 100644
--- a/toolkit/themes/shared/popupnotification.inc.css
+++ b/toolkit/themes/shared/popupnotification.inc.css
@@ -160,6 +160,7 @@ popupnotification {
 .panel-footer > button:not([disabled])[default] {
   color: var(--button-primary-color);
   background-color: var(--button-primary-bgcolor);
+  --focus-outline-color: var(--button-primary-bgcolor);
 }
 
 .panel-footer > button:not([disabled])[default]:hover {