How to customize Firefox and make it simple and elegant on macOS

Mozilla has been working on a major UI redesign project for Firefox called "Nova".

You can obtain "Nova" from the /firefox/nightly/maple repository and try it by configuring it as follows:

browser.design-tokens.nova to true;
browser.newtabpage.activity-stream.nova.enabled to true;
browser.urlbar.nova.featureGate to true;
browser.urlbar.quicksuggest.ampTopPickUseNovaIconSize to true;

"Account and sync" section in the "Sync" category settings. (Firefox 151.0)

"Account and sync" section of "Sync"

How to Disable Split Screen View in Firefox

To disable Split Screen View, please configure it as follows:

browser.tabs.splitView.enabled to false;

Mozilla has planned to redesign Firefox's settings User Interface. (Firefox 149.0)

To enable New Settings Page Redesign UI, please configure it as follows:

browser.settings-redesign.enabled to true;

"Fonts" section in the "General" category settings of the new UI design

"Fonts" section in "General"

"Browser Layout" section in the "General" category settings of the new UI design

"Browser Layout" section in "General"

"Website language" section in the "General" category settings of the new UI design

"Website language" section in "General"

"Language - Spell check" section in the "General" category settings of the new UI design

"Language - Spell check" section in the "General"

"Applications" section in the "General" category settings of the new UI design

"Applications" section in "General"

"Homepage" & "Firefox Home" section in the "Home" category settings of the new UI design

"Homepage" & "Firefox Home" section in the "Home"

"Additional search engines" section in the "Search" of the new UI design

"Additional search engines" section in the "Search"

"Browser Privacy" section in the "Privacy & Security" category settings of the new UI design

"Browser Privacy" section in the "Privacy & Security" - Case 1 -

"Browser Privacy" section in the "Privacy & Security" - Case 2 -

"Advanced settings" part in the "Enhanced Tracking Protection" section

"Customize tracking protection" part in the "Advanced settings" section

"Sync" section in the "Sync" category settings of the new UI design

"Sync" section of "Sync"

A new "AI Controls" category has been added to the settings. (Firefox 149.0)

"about:preferences#ai"

"New Tracking Protection Icon and Panel" is now available. (Firefox 145.0 and later)

To enable this feature, please configure it as follows:

browser.urlbar.trustPanel.featureGate to true;

Since the bug 1917305 was implemented in the nightly builds, this feature has been enabled by default.
(Firefox 148.0)

"the New Tracking Protection Panel"

Added experimental feature "Customizable Hotkeys". (Firefox 147)

With the implementation of bug 1635774 in nightly builds, the "customizable hotkeys" feature has been added experimentally as "about:keyboard".

"about:keyboard"

The "Privacy and Security" category settings have been redesigned. (Firefox 147)

"Cookies and Site Data" section of "Privacy and Security"

"Permissions" section of "Privacy and Security"

Added "Local Network Devices" section to "Preferences Privacy". (Firefox 143)

"Permissions" - "about:preferences#privacy"

The positions of the toggle buttons and labels.

Since the bug 1917305 was implemented in Nightly, the position of the toggle button on the Tracking Protection Panel has been reversed from left to right.

I think it would be better to place the label on the left side of the toggle switch for clarity, so I will undo the change.

"the Tracking Protection Panel"

How to disable AI-powered Smart tab grouping (Firefox 141.0)

If you want to disable it, you set as follows:

browser.tabs.groups.smart.enabled to false;

Added "Contrast Control" section to "Preferences General" instead of "Color section". (Firefox 138)

"Profiles" - "about:preferences#general"

"Profiles" section has been added to "Preferences General". (Firefox 137)

"Profiles" - "about:preferences#general"

The "Sidebar & Vertical tabs" has been removed from "Firefox Labs" and moved to the "Browser Layout" section of "Preferences General". (Firefox 136)

"Browser Layout" - "about:preferences#general"

In Reader View, the new "Text Formatting Controls" and "Theme Controls" are now the default, and "Read Aloud Controls" has been updated.

How to disable Tab Groups (Firefox 135.0)

If you want to disable it, you set as follows:

browser.tabs.groups.enabled to false;

Always show "Unified Search Button" (Firefox 135.0)

If you want to enable it, you set as follows:

browser.urlbar.unifiedSearchButton.always to true;

Upcoming New "Profile Manager" & "Edit Profile". (Firefox 134)

"Upcoming New Profile Manager"

"Upcoming New Edit Profile"

How to enable Tab Groups (Firefox 133.0)

If you want to enable it, you set as follows:

browser.tabs.groups.enabled to true;

A bug reported 24 years ago has finally been fixed. (Firefox 132)

The bug 71895 reported 24 years ago has finally been fixed.
Bravo!

Now you can try "Sidebar" and "Vertical tabs" in "Firefox Labs". (Firefox 131)

"Firefox Labs" - "about:preferences#experimental"

"Nightly Experiments" has been renamed to "Firefox Labs" and redesigned. (Firefox 130)

"Firefox Labs" - "about:preferences#experimental"

"Command+F" to open and close FindBar (Firefox 129.0)

Since browser-command-listeners.js has been removed from the repository, apply the following patch:

--- a/browser/content/browser-sets.js
--- b/browser/content/browser-sets.js
@@ -98,7 +98,7 @@
             PictureInPicture.onCommand(event);
             break;
           case "cmd_find":
-            gLazyFindCommand("onFindCommand");
+            if (gFindBar) gFindBar.hidden ? gFindBar.onFindCommand() : gFindBar.close(); else gLazyFindCommand("onFindAgainCommand");
             break;
           case "cmd_findAgain":
             gLazyFindCommand("onFindAgainCommand", false);

You can add a chatbot of your choice to the sidebar. (Firefox 129)

If you want to activate this:
Go to "about:preferences#experimental" and turn the AI Chatbot Integration experiment on.

See "Experimenting with AI services in Nightly – Firefox Nightly News" for more information.

"AI Chatbot Integration" parts of "about:preferences#experimental"

Urlbar Search Mode Switcher (Firefox 129.0)

If you want to try it, you set as follows:

browser.urlbar.scotchBonnet.enableOverride to true;

browser.urlbar.searchModeSwitcher.featureGate to true;

Redesigned Sidebar on Nightly (Firefox 128.0) and Vertical Tabs (Firefox 129.0)

If you want to enable those, you set as follows and relaunch Nightly:

sidebar.revamp to true;
sidebar.verticalTabs to true;

Disable Tab Hover Previews (Firefox 128.0)

Since the bug 1893676 has ridden on the Nightly train, you set as follows:

browser.tabs.hoverPreview.enabled to false;
browser.tabs.hoverPreview.showThumbnails to false;

New Profile Manager option added to the Hamburger Menu (Firefox 128.0)

If you want to enable it, you set as follows:

browser.profiles.enabled to true;

"Command+F" to open and close FindBar (Firefox 128.0)

Since the bug1897477 has ridden on the Nightly train, apply the following patch:

--- a/browser/content/browser-command-listeners.js
+++ b/browser/content/browser-command-listeners.js
@@ -87,7 +87,7 @@
     PictureInPicture.onCommand(event);
   },
   cmd_find() {
-    gLazyFindCommand("onFindCommand");
+    if (gFindBar) gFindBar.hidden ? gFindBar.onFindCommand() : gFindBar.close(); else gLazyFindCommand('onFindAgainCommand');
   },
   cmd_findAgain() {
     gLazyFindCommand("onFindAgainCommand", false);

Enable text formatting controls for Reader Mode! (Firefox 127.0)

If you want to enable it, you set as follows:

reader.improved_text_menu.enabled to true;

"Customizing Reader Mode" is now available in Reader View! (Firefox 126.0)

If you want to enable it, you set as follows:

reader.colors_menu.enabled to true;

"search-config-V2" is now enabled on Nightly! (Firefox 126.0)

If you want to disable it, you set as follows:

browser.search.newSearchConfig.enabled to false;

Test version of Sidebar Launcher now available for trial!

If you would like to try it out, you can download it here:
https://ftp.mozilla.org/pub/firefox/nightly/latest-larch/

And the latest shortlog is here:
https://hg.mozilla.org/projects/larch/shortlog

Sidebar Launcher

Sidebar Launcher and Tab Strip

Now Tab Previews are available! (Firefox 124.0)

If you want to test Tab Previews, you set as follows:

browser.tabs.cardPreview.enabled to true;
browser.tabs.cardPreview.showThumbnails to true;

"Address Bar – Firefox Suggest" has been moved to "Search Preferences". (Firefox 123.0)

"Search Suggestions" and "Address Bar" parts of "about:preferences#search"

The "Search Bar" part of "about:preferences#search" has been removed. (Firefox 122.0)

If you want to add a "search bar" to the toolbar, you can do so in "Customize Toolbar…".

"Address bar suggestion toggle button" has been unified into a "check box." (Firefox 121.0)

"Address bar suggestion toggle button" has been unified into a "check box"

How to simplify the use of the "Reset Private Browsing Session" button. (Firefox 120.0)

If you want to simplify the use of the "Reset Private Browsing Session" button, you set as follows:

browser.privatebrowsing.resetPBM.enabled to true;
browser.privatebrowsing.resetPBM.showConfirmationDialog to false;

Add the following to userChrome.css:

#reset-pbm-toolbar-button:not(:hover) {
  opacity: 0 !important;
}

#confirmation-hint {
  display: none !important;
}

Disable "Firefox View" and hide "Firefox View Button". (Firefox 119.0)

If you want to disable "firefox view" and hide firefox-view-button, you only set as follows:

browser.tabs.firefox-view to false;
browser.tabs.firefox-view-next to false;

"Enhanced Tracking Protection" has a new option in "about:preferences#privacy". (Firefox 118)

New option in "Enhanced Tracking Protection"

Firefox brings an automatic language translator for websites. (Firefox 117.0)

Translator Panels

A new tabability part has been added to the about:preferences on macOS. (Firefox 117.0)

Tabability part in "about:preferences"

A new "Run on protected websites" part has been added to the about:addons. (Firefox 116.0)

"Run on protected websites" part in "about:addons"

A new "Translations" part has been added to the about:preferences. (Firefox 115.0)

Translations part in "about:preferences#general"

A new "DNS over HTTPS" part has been added to the about:preferences. (Firefox 114.0)

DNS over HTTPS part in "about:preferences#privacy"

A new "Speaker Selection" button has been added to the about:preferences. (Firefox 113.0)

"Speaker Selection" button in "about:preferences#privacy"

A new "Import Data" button has been added to the about:preferences. (Firefox 113.0)

"Import Data" button in "about:preferences#general"

A new "Import Data Migration Wizard" in the about:preferences. (Firefox 113.0)

A new "Import Data Migration Wizard" modal window in "about:preferences#general"

Enable "Address Bar Suggest Toggle Buttons" (Firefox 111.0)

If you want to enable the "Address Bar Suggest Toggle Buttons" in "about:preferences#privacy",
do the following:

browser.urlbar.quicksuggest.enabled to true

"Address Bar Suggest Toggle Buttons" in "about:preferences#privacy"

Enable the "Cookie Banner Reduction" User Interface (Firefox 111.0)

If you want to enable the "Cookie Banner Reduction" user interface, do the following and check
"Reduce Cookie Banners" in "about:preferences#privacy".

cookiebanners.ui.desktop.enabled to true;

"Cookie Banner Reduction" User Interface (1)

"Cookie Banner Reduction" User Interface (2)

Remove "Extensions" Menu Button in Firefox Toolbar (Firefox 111.0)

The "extensions.unifiedExtensions.enabled" pref has been removed in Firefox 111.0, so if you want to remove the "Extensions" Menu Button, you can use userChrome.css as follows instead;

#unified-extensions-button {
  display: none !important;
}

Remove "Extensions" Menu Button in Firefox Toolbar (Firefox 109.0)

If you want to remove "Extensions" Menu Button, you only set as follows:

extensions.unifiedExtensions.enabled to false;

Enable Firefox to automatically reject cookie banners (Firefox 108.0)

If you want Firefox to automatically reject cookie banners, you only set as follows:

cookiebanners.service.mode to 2;
cookiebanners.service.mode.privateBrowsing to 2;

Disabble Dark Mode and use Light Mode in Private Windows (Firefox 106.0)

If you want to disable Dark mode in private windows, you only set as follows:

browser.theme.dark-private-windows to false;

Disable and hide "Firefox View Button" (Firefox 106.0)

If you want to disable and hide firefox-view-button, you only set as follows:

browser.tabs.firefox-view to false;

Enable "Alltabs Button" to the classic style (Firefox 106.0)

If you want to enable the classic style of alltabs-button, you only set as follows:

browser.tabs.tabmanager.enabled to false;

Restore Classic Keyboard Behavior for Toolbar Navigation (Firefox 103)

If you want to restore classic keyboard behavior, you only set as follows:

browser.toolbars.keyboard_navigation to false;

Force Firefox to not open download panel automatically (Firefox 98.0)

If you want to not opendownload panel automatically, you only set as follows:

browser.download.alwaysOpenPanel to false;

Enable the native MacOS Contextual Menu (Firefox 89.0)

If you want to enable the native MacOS Contextual Menu, you only set as follows:

widget.macos.native-context-menus to true;

Enable the new Proton Design Contextual Menu (Firefox 89.0)

If you want to enable the new Proton Design Contextual Menu, you only set as follows:

browser.proton.enabled to true;

Enable the new Proton Design AppMenu (Firefox 88.0)

If you want to enable the new Proton Design AppMenu, you only set as follows:

browser.proton.enabled to true;

Enable the new Proton Design AppMenu (Firefox 87.0)

If you want to enable the new Proton Design AppMenu, you will need to manually set as follows:

browser.proton.appmenu.enabled to true;

Disable the new Proton Design Tabs (Firefox 87.0)

If you want to disable the new Proton Design Tabs, you will need to manually set as follows:

browser.proton.tabs.enabled to false;

Re-enable the Backspace shortcut (Firefox 86.0)

If you want to re-enable the Backspace shortcut for "Go back one page", you will need to manually set as follows:

browser.backspace_action to 0;

Force Firefox to always use Light or Dark Theme Mode

If you want to force Firefox to always use Light theme mode, you will need to manually set as follows:

ui.systemUsesDarkTheme to 0;

If you want to force Firefox to always use Dark theme mode, you will need to manually set as follows:

ui.systemUsesDarkTheme to 1;

Enable Fission in Firefox

If you want to try Firefox's Site Isolation feature Fission, you will need to manually set as follows:

fission.autostart to true;
gfx.webrender.all to true;

Enable to reveal the Firefox Experiments page

If you want to reveal and add the Firefox Experiments page, you will need to manually set as follows:

browser.preferences.experimental to true;

Enable to use userContent.css and userChrome.css

Since the bug 1541233 landed on Firefox Nightly repository, Firefox doesn't allow use of userChrome.css or userContent.css files by default.
To use these files for Firefox customization, you will need to manually set as follows:

toolkit.legacyUserProfileCustomizations.stylesheets to true;