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Firefox: tabs on bottom (third time around)

3770 hits Updated: 31 May 2020 Blog
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Firefox Quantum (Firefox 69) uses tabs on top

How to place tabs on bottom

Taming the dragon:  enabling the CSS

This article shows you how to change Firefox’s appearance from tabs on top (where the tabs appear above the URL address bar) to display the tabs below the URL address bar.

Before the release of Firefox v57, it was possible to change the location of the tabs by changing a browser parameter setting.  The setting was

browser.tabs.onTop = false

FF still retains that setting but its functionality has been disabled; browser tabs remain on top (above the URL address bar) regardless of this parameter’s value.  We will see how it’s possible to change the location of the tabs.My earlier articles—Firefox: tabs on bottom and Firefox: tabs on bottom (again)—discuss Firefox before v69.  This article updates that advice following the release of FF69.

Tabs on top vs. on bottom

The following image shows the difference between tabs on top, which is the new behaviour for FF (shown on the left), and tabs on the bottom (shown on the right).  It is a matter of personal choice whether people prefer one style over the other.

ff57 tabs

To change the behaviour so that the tabs appear on the bottom we will need to write a small piece of CSS and store the file on your computer as well as make one small change to Firefox‘s “secret” settings.

Creating the CSS file

Locating your Firefox browser profile

Press the keyboard characters ⊞ Win + R to bring up the Run dialog.

FF profiles windowsType %APPDATA%\Mozilla\Firefox\Profiles in the text box and press OK.  This will open Windows Explorer (see the image on the right; click to enlarge it).

You should see a folder with the name xxxxxxxx.default (or possibly xxxxxxxx.default-nnnnnnnnnnnnn) where xxxxxxxx are randomly-generated characters and nnnnnnnnnnnnn is the epoch timestamp representing the date/time when the folder was created.

ff profile chromeThe next thing to do is to navigate within this just-named, folder.  Look for a sub-folder named /chrome (see the image on the right for more information).  Navigate into that folder.

It is highly probable that there will be no files within the chrome folder.  The next thing we will do is create a new file named userChrome.css.  Open an instance of Windows Notepad, select the code segment below and paste this text into Notepad.

/* TABS: on bottom */
#navigator-toolbox toolbar:not(#nav-bar):not(#toolbar-menubar) {-moz-box-ordinal-group:10}
#TabsToolbar {-moz-box-ordinal-group:1000!important}

#TabsToolbar {
position: absolute !important;
bottom: 0 !important;
width: 100vw !important;
display: block !important;

hbox tab {
background-color: #eee !important;
color: hsl(210, 77%, 47%) !important;

hbox tab:hover, hbox tab:active, hbox tab:focus {
color: #191970 !important;

.tab-content[selected="true"] {
color: #191970 !important;

#tabbrowser-tabs {
top: 300 !important;
width: 100vw !important;
#main-window:not([chromehidden*="toolbar"]) #navigator-toolbox {
padding-bottom: calc(1px + var(--tab-min-height_tnot)) !important;

/* TABS: height */
:root {
--tab-toolbar-navbar-overlap: 0px !important;
--tab-min-height: 33px !important; /* adjust to suit your needs */
--tab-min-height_tnot: 32px;
:root #tabbrowser-tabs {
--tab-min-height: 33px !important; /* needs to be the same as above under :root */
--tab-min-width: 80px !important;

#TabsToolbar {
height: var(--tab-min-height) !important;
margin-bottom: 1px !important;
box-shadow: ThreeDShadow 0 -1px inset, -moz-dialog 0 1px !important;
background-color: var(--toolbar-bgcolor) !important;
/* hide windows-controls */
#TabsToolbar #window-controls {display:none!important;}

/* move caption buttons to right of Tab bar */
#main-window[tabsintitlebar]:not([inFullscreen="true"]) #toolbar-menubar[autohide="true"] ~ #TabsToolbar .titlebar-buttonbox-container {
position: fixed !important;
right: 0 !important;
top: calc(6px + var(--tab-min-height)) !important;
display: block !important;
visibility: visible !important;
#toolbar-menubar[autohide="true"] ~ #TabsToolbar {padding-right: 100px !important;}

Save the file with the name userChrome.css.

“Enabling” the CSS

There’s a new “feature” built into FF since v69https://www.ghacks.net/2019/05/24/firefox-69-userchrome-css-and-usercontent-css-disabled-by-default/.  Before you are able to use the file userChrome.css you will need to tame another one of the “Firefox dragons”.  The additional setting that you will need to change is

toolkit.legacyUserProfileCustomizations.stylesheets = true

Make the changes, close all existing instances of Firefox—i.e. close all windows that are running FF—and then open a new instance; effectively “restart” Firefox.  You should now see the tabs on the bottom.

About the author:

is a website hobbyist specialising in Joomla, a former member of the Kunena project for more than 8 years, and an active contributor on The Joomla Forum™. The opinions expressed in this article are entirely those of the author. View his profile here.

2 thoughts on “Firefox: tabs on bottom (third time around)”

  1. Sunday, 08 December 2019 22:53

    This applies to Firefox 71.0 for tabs on bottom.


    1. Sunday, 31 May 2020 20:32
      The solution you've mentioned is only half-complete. I've added a new article today that should work (see /blog/93-firefox-tabs-on-bottom-3). I should also mention that we are now using FF76

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