--- a/browser/themes/shared/notification-icons.inc.css
+++ b/browser/themes/shared/notification-icons.inc.css
@@ -36,17 +36,17 @@
 }
 
 .popup-notification-icon {
   width: 64px;
   height: 64px;
   margin-inline-end: 10px;
 }
 
-#notification-popup-box > .notification-anchor-icon:hover {
+#notification-popup-box > .notification-anchor-icon:not(.in-use):hover {
   fill: #606060;
 }
 
 /* INDIVIDUAL NOTIFICATIONS */
 
 /* For the moment we apply the color filter only on the icons listed here.
    The first two selectors are used by socialchat.xml (bug 1275558). */
 .webRTC-sharingDevices-notification-icon,
@@ -269,17 +269,17 @@
 /* PLUGINS */
 
 .plugin-icon {
   list-style-image: url(chrome://browser/skin/notification-icons.svg#plugin);
 }
 
 .plugin-icon.plugin-blocked {
   list-style-image: url(chrome://browser/skin/notification-icons.svg#plugin-blocked);
-  fill: #d92215;
+  fill: #d92215 !important; /* important! to override the default hover color */
 }
 
 #notification-popup-box[hidden] {
   /* Override display:none to make the pluginBlockedNotification animation work
      when showing the notification repeatedly. */
   display: -moz-box;
   visibility: collapse;
 }