What toolbar(s) is this about ?

You can right-click empty toolbar area and make sure "Hide Toolbars" has a tick.

Related control pref on about:config page.

• browser.fullscreen.autohide = true

One other note:

If the cursor is in the address bar when you press F11, the toolbar needs to remain visible so you can type. Make sure the cursor is in the page before pressing F11.

The firefox toolbar when I scroll to the top of the screen.

Did you right click in the toolbar area and made sure that autohide is enabled like I wrote above ?

Is there any other way to make the fullscreen function like chrome?

Is there any other way to make the fullscreen function like chrome?

Do you mean, when you move the mouse pointer to the top of the screen, instead of rolling down the toolbar area, show a button to exit full screen mode?

There is no built-in settings for that. userChrome.css would be your best bet. What set of rules did you try and what result did you get?

I tried with this: @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

1. fullscr-toggler {display:none!important}

From https://support.mozilla.org/en-US/questions/1300961

In what cases do you want to hide the toolbar(s) ?

Are the toolbars visible or hidden when you set focus to the webpage area ?

Hiding the #fullscr-toggler element like you posted above should prevent the toolbar from showing when you move the mouse to the top.

userChrome does not work.

Could you double-check your userChrome.css file against the steps in my article here to make sure it is in the proper location and Firefox is set to look for it at startup:

https://www.userchrome.org/how-create-userchrome-css.html

It is not that difficult to create userChrome.css if you have never used it.

The first step is to open the "Help -> Troubleshooting Information" page and find the button to access the profile folder.

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

You can find this button under the "Application Basics" section as "Profile Folder -> Open Folder". If you click this button then you open the profile folder in the Windows File Explorer. You need to create a folder with the name chrome in this folder (name is all lowercase). In the chrome folder you need to create a plain text file with the name userChrome.css (name is case sensitive). In this userChrome.css text file you paste the text posted. In Windows saving the file is usually the only time things get more complicated because Windows can silently add a .txt file extension and you end up with a file named userChrome.css.txt. To avoid this you need to make sure to select "All files" in the dialog to save the file in the text editor using "Save File as".

You need to close (Quit/Exit) and restart Firefox when you create or modify the userChrome.css file.

See also:

• https://www.userchrome.org/what-is-userchrome-css.html
• https://www.userchrome.org/how-create-userchrome-css.html

In Firefox 69 and later you need to set this pref to true on the about:config page to enable userChrome.css and userContent.css in the chrome folder.

• toolkit.legacyUserProfileCustomizations.stylesheets = true

See:

• https://www.userchrome.org/firefox-changes-userchrome-css.html

Thanks!