diff --git a/firefox/treestyletab.css b/firefox/treestyletab.css
index fe12b62..c1f6d66 100644
--- a/firefox/treestyletab.css
+++ b/firefox/treestyletab.css
@@ -35,6 +35,7 @@
 /* Pined tabs container */
 #pinned-tabs-container {
   border-bottom: 1px solid rgb(173, 173, 173);
+  transition: none;
 }
 
 /* Tabs */