diff --git a/skin/classic/treestyletab/ui-base.css b/skin/classic/treestyletab/ui-base.css
index 7ffa1de4..3a31d5f3 100644
--- a/skin/classic/treestyletab/ui-base.css
+++ b/skin/classic/treestyletab/ui-base.css
@@ -420,9 +420,12 @@ tabbrowser[treestyletab-tabbar-position="bottom"]
 	display: none;
 }
 
-.tabbrowser-tab[treestyletab-highlighted='true'] {
-	outline: Highlight solid 0.2em;
+.tabbrowser-tab[treestyletab-highlighted] {
+	outline: transparent solid 0.2em;
 	outline-offset: -0.2em;
 	-moz-outline-radius: 0.25em;
 	outline-radius: 0.25em;
 }
+.tabbrowser-tab[treestyletab-highlighted='notifying'] {
+	outline: Highlight solid 0.2em;
+}