Jiff Slater
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30 Jul 2021
These articles have been archived. You may find them useful but I am no longer offering support for them. Check out my latest articles on plkt.io.
My favourite tweaks for Firefox
8 July 2021

I’ve been using Firefox for the good part of 15 years and over the years I’ve collected a few particular preferences for how I use the application. I’ve grouped them below and tried where possible to make them applicable to the latest available versions.


In this file you can configure modifications to the stylesheet used to render the Firefox UI. It’s stored in your profile directory in a directory called chrome.

Before you create the file, go ahead and enable support for the file in about:config by setting the toolkit.legacyUserProfileCustomizations.stylesheets boolean preference to true.

In this file, I’ve configured the following:

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

/* Pulled from https://support.mozilla.org/de/questions/1239330 and sets the minimum width of pinned tabs */
.tabbrowser-tab[pinned] {width: 45px !important;}
.tab-label-container[pinned] {visibility: hidden !important;}

/* Pulled from https://github.com/piroor/treestyletab/wiki/Code-snippets-for-custom-style-rules#for-userchromecss and hides the top tab bar */
#tabbrowser-tabs {
visibility: collapse !important;

/* Pulled from above website. This removes the large sidebar header specifically for Tree Style Tabs */
#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
display: none;

/* Make that tab listing a bit smaller */
#sidebar {
min-width: 100px !important;

Company density

I took this one straight from userChrome.org so you can follow there. In a nutshell, you can edit the browser.uidensity setting in about:config and set it to one of the following options:

Along with the above (while I can) I’ve turned off the new proton UI by setting the browser.proton.enabled to false. I imagine at some point this won’t work, so I’ve also configured the back up option which reduces the spacing between menu items by setting browser.proton.contextmenus.enabled to false.

Further settings in about:config.