No Close Buttons

Firefox 57 and later

Firefox 57 and later do not support any API to make this extension work. If you prefer your browser tabs without close buttons, you can make it work by adding a custom userChrome.css file to your Firefox profile:

1. Find your profile folder

2. Create a directory called chrome inside it if one does not already exist

3. Create a file named userChrome.css in the new directory

4. Add the following CSS code to it:

   @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
   .tab-close-button { display: none !important; }

5. Open "Advanced Preferences" by typing about:config in the address bar.

6. Search for toolkit.legacyUserProfileCustomizations.stylesheets and set it to true.

7. Restart Firefox

History

In Firefox 31, the browser.tabs.closeButtons option was removed. This restartless addon forces what previously used to be a value of 2 for that option: no close buttons on any tabs.