diff --git a/prefs.js b/prefs.js
index 7e7ec3b..2a13f0f 100644
--- a/prefs.js
+++ b/prefs.js
@@ -9,6 +9,8 @@ user_pref("general.autoScroll", true);
 user_pref("browser.toolbars.bookmarks.visibility", "never");
 /* Rozložení prohlížeče */
 user_pref("browser.uiCustomization.state", "{\"placements\":{\"nav-bar\":[\"back-button\",\"forward-button\",\"stop-reload-button\",\"urlbar-container\",\"downloads-button\",\"fxa-toolbar-menu-button\",\"ublock0_raymondhill_net-browser-action\"],\"toolbar-menubar\":[\"menubar-items\"],\"TabsToolbar\":[\"panorama-tab-groups_example_com-browser-action\",\"tabbrowser-tabs\",\"new-tab-button\",\"alltabs-button\"]},\"currentVersion\":18}");
+/* Zapnutí podpory CSS úprav rozhraní */
+user_pref("toolkit.legacyUserProfileCustomizations.stylesheets", true);
 
 
 /**