diff --git a/chrome/userChrome.css b/chrome/userChrome.css
index c20b524..4c5fe4f 100644
--- a/chrome/userChrome.css
+++ b/chrome/userChrome.css
@@ -10,6 +10,11 @@
   border-bottom: none !important;
 }
 
+#tabbrowser-tabbox {
+  box-shadow: none !important;
+  outline: none !important;
+}
+
 /* Windows overrides */
 @media (-moz-platform: windows) {