Hi, Starting in Firefox 89, Compact Mode is no longer supported. If you've been using Compact Mode on a previous version, you should be able to retain the feature. However, for the best experience, we encourage you to use the default Density setting. If you are an advanced user, it's still possible to activate it in the [[Configuration Editor for Firefox|Configuration Editor]] (''about:config'' page). #Type '''about:config''' in the address bar and press Return. A warning page may appear. Click '''Accept the Risk and Continue''' to go to the about:config page. #Find the ''browser.compactmode.show'' preference. #Switch the toggle to '''true''' and then close the tab. #Click on the menu button [[Image:fx89menu]] to open the menu panel. #Click '''More Tools''' menu. #Choose '''Customize Toolbar'''. #At the bottom of the panel, click the Density button. #Choose '''Compact (not supported)''' from the menu options. #Click '''Done'''. More about that: [[Compact mode workaround in Firefox]]