Add code to the userChrome.css file below the default @namespace line.

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

.browserContainer > .browserStack > browser {
 overflow-y: scroll;
 margin-right: -14px;
}

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

Hi cor-el This is what my userchrome looks like

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

.browserContainer > .browserStack > browser {

overflow-y: scroll;
margin-right: -14px;

}

Can you see where I am going wrong please?

I have attached an image showing its location etc.

Thanks

The name of the file is userChrome.css with a capital 'C' (you have userchrome.css).

Hi cor-el

I have renamed it and restarted firefox however the scrollbar remains.

Can you see anything else wrong please?

Thanks

Try to add the !important as that may be required on window to override exiting rules.

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

.browserContainer > .browserStack > browser {
 overflow-y: scroll !important;
 margin-right: -14px !important;
}

Hi Cor-el

Still no luck

Thanks