Hi ria1039, unfortunately, it isn't possible for an add-on to make the changes because Firefox 57+ does not let them make major structural changes to the interface.

The userChrome.css approach for moving the tab bar is roughly the same for Firefox 57-64. It will change in Firefox 65. That means lots of people have successfully done it, there are demo videos, and you can also get help customizing it to your needs.

Here are the steps again:

(A) Create a new chrome folder in your profile folder

The following article has the detailed steps for that (#1, #2, and I recommend #3)

https://www.userchrome.org/how-create-userchrome-css.html

I also created videos for both Windows and Mac, on that same page.

(B) Set your OS to show file extensions

See Step #4 in the above article.

(C) Download the following file and move it into your new chrome folder

Firefox 57-64 (Windows and Mac): https://www.userchrome.org/samples/userChrome-tabs_on_bottom.css

Firefox 65+ (Windows): https://www.userchrome.org/samples/userChrome-tabs_on_bottom_Fx65.css

Firefox 65+ (Mac): See: Custom CSS tweaks for Firefox Quantum.

(D) Rename the file to just userChrome.css

Windows: You can right-click the file, then Rename, then remove the -tabs_on_bottom or -tabs_on_bottom_Fx65 part from the file name so you end up with exactly userChrome.css and then click away to complete the edit.

Mac: To make the name of a file editable, you can select the file in Finder and press Return, or you can "force-click" it if you have one of the new touchpads. Remove the -tabs_on_bottom part from the file name so you end up with exactly userChrome.css and then click away to complete the edit.

The next time you exit Firefox and start it up again, it should discover that file and apply the rules.

Thanks, I had tried this before, or at least thought I had, but it didn't work, however this time it has, many thanks.

I am tired of spending hours trying to keep Firefox useful. I have reinstalled 64.02 so my tabs are where they belong. I have locked out updates until the tabs on bottom is fixed permanently or I find another browser that cares about how useful their product is. hopefully I won't need to switch browsers. Mozilla used to care about its users. That is why I have used it all these years. Too bad they no longer care and think some standard written by people who do not use the product for a living know more than the everyday users of their product.

Try putting this code in the userChrome.css file. I tested it using Firefox 59 and 65 under Windows 10. The first ":root" block is not really necessary, but it improves the shadowing of the font.

:root, .tabbrowser-tab { 

text-shadow: none !important;

}

:root[uidensity=compact] { 

--tab-min-height_tnot: 28px;

}

#main-window:not([chromehidden*="toolbar"]) #navigator-toolbox { 

padding-bottom: calc(1px + var(--tab-min-height_tnot)) !important;

}

#TabsToolbar { 

position: absolute !important; bottom: 0 !important; width: 100vw !important;

}