Software I like: Firefox

Firefox logo

These notes are aimed at Firefox for the desktop (as opposed to mobile phones).


Download an installer and run it. Full off-line installers for various systems and languages can be downloaded from here. Older versions can be downloaded from here but that is strongly discouraged.

Before installing Firefox, you may want to first check the latest release notes or all release notes to find out about recent changes and fixes.


Some settings are accessible by typing about:preferences in the URL bar and pressing the Enter key, or by doing Edit ► Preferences in Linux or Tools ▶ Settings in MS Windows. More advanced preferences are accessible by typing about:config in the URL bar and pressing the Enter key. A warning message may need to be acknowledged. Click on Show All to see the very long complete list of settings, or use the Search box to filter the list. See also Configuration Editor for Firefox for instructions; about:config for more detail, about:config_entries ‘where the most important about:config variables are described; and for a longer (but still not complete and up-to-date) list. See also Customizing Firefox Using policies.json for administrators configuring Firefox across multiple computers.

After installation, you may want to do some or all of the following.



Of the many available add-ons, these are ones that I have installed:

Versions 57+

With version 57 (Quantum) a lot of things changed (ref), including a new multi-process core engine (Electrolysis), a new CSS engine (Stylo), a new GUI (Photon), and the dropping of support for the legacy XPCOM- and XUL-based extension systems in favour of the WebExtension API copied from Google Chrome (ref).

The user interface can now be customized using a file chrome/userChrome.css in the user's profile directory (see about:profiles). Instructions and examples abound (e.g., UserChrome.css at mozillaZine; Similarly, the appearance of Web pages can be customized using userContent.css. Starting with Firefox 69, toolkit.legacyUserProfileCustomizations.stylesheets must be set to true in about:config for userChrome.css and userContent.css to work. (The @namespace line is sometimes said to be required but is omitted by many (refs 1, 2). CSS code can be added directly into user*.css or invoked using @import (ref).

Square tabs
Curved tabs 1
Curved tabs 2
Curved tabs 3
One annoying esthetic issue is that the tabs are square (top screenshot on the right), instead of the curved shape that was introduced (and initially objected to) in the Australis design of Firefox 29. I have found two examples of how to do this, one by Axy_David (second screenshot), which has some problems with the tabs themselves and with other things, like the Back and Forward buttons; and Photon Australis by wilfredwee (third screenshot) which seems to be more successful but doesn't have separators between inactive tabs. An enhancement by teijiIshida (fourth screenshot), based on Photon Australis version 0.3.0 dated 2017 Nov 18, provides curved borders for inactive tabs.

The status bar at the bottom of the window now only shows up transiently. userChrome.css is intended to make it permanent (ref). I haven’t made it work yet.

Firefox now comes with a stupidity called Pocket. There are two aspects of it, which need to be disabled separately (ref):

Versions 29+

Many interface changes arrived with version 29 (Australis). One of the big debates was about whether tabs should be on top or on the bottom; they had been on the top by default for a long time but until version 29 there was a built-in method of moving them to the bottom. The delineation of the tabs also changed from straight lines to curves. To undo some of the interface changes, one option was the Classic Theme Restorer add-on. This add-on doesn't work in Firefox 57+.

R. Funnell
Last modified: 2022-05-28 11:53:43