diff --git a/sidebar-remove-browser-outline.css b/sidebar-remove-browser-outline.css
new file mode 100644
index 0000000..0020a45
--- /dev/null
+++ b/sidebar-remove-browser-outline.css
@@ -0,0 +1,7 @@
+/* Remove the built in Browser box outline and box shadow which looks a bit odd with sidebar. [[OPTIONAL]] */
+#tabbrowser-tabbox {
+   @media (-moz-bool-pref: "sidebar.revamp") {
+      outline: none !important;
+      box-shadow: none !important;
+   }
+}