I want to automatically hide the firefox ui until I mouse hover the top of my browser window without having to full screen.

I love the windows task bar auto hide feature and hate that I cant find a browser where I can seemingly easily set this up.

Does anyone know how to realize this with Chrome or Firefox browsers? There seems to be no extensions for it I can find.

Thanks for the help.

  • I'm not aware of an add-in to do it, but this might work in Firefox.
    – Worthwelle
    Jul 19, 2019 at 14:30

1 Answer 1


I've got something that works, based on the classic userChrome.css technique that people used to use all the time on older versions of Firefox, and still works today if you enable it in about:config. It's based on a Gist link found on Reddit here and adapted to make it work on maximized windows.

Follow this guide on how to set up your userChrome...

  • Adding the chrome directory in the right place in your profile folder
  • Making the file
  • Setting toolkit.legacyUserProfileCustomizations.stylesheets to true about:config so Firefox will use it when loaded.

Put the following code into your userChrome.css:

  #navigator-toolbox {
    position: relative;
    height: 15px;
    margin-bottom: -5px;
    opacity: 0;
    overflow: hidden;

  #navigator-toolbox:hover {
    height: auto;
    margin-bottom: 0px;
    opacity: 1;
    overflow: show;


Window without hover

Window with hover

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .