Enter about:config in the URL bar and set layout.css.devPixelsPerPx = 1.5.

You can set a value wchich is convenient for you.

Hello Warthog-Fan,

And so we meet again .....

Here's the version for Firefox (the developer even mentions Thunderbird-users under "About this extension") :

https://addons.mozilla.org/en-US/firefox/addon/theme-font-size-changer/

I hope this will do what you want, but I thought you might also like to take a look at this add-on :

https://addons.mozilla.org/en-US/firefox/addon/nosquint-plus/

Any good  ?

For elements in the user interface you can only do this via layout.css.devPixelsPerPx like posted above. This pref accepts 0.05 (5%) value increments so you can adjust the value of this pref until you are satisfied. Double check any changes you make to this pref because a misplaced decimal point or a too low value will cause serious issues.

If you need to correct the zooming on web pages after adjusting this pref then you can use an extension like posted by McCoy.

Using the Theme and Font Size Changer as referenced by McCoy, above doesn't seem to allow me to do anything except change the Theme Background and Color. The lower part of the windows just says that most of the functions of the Add-on don't work any more.

I did enter the about:config command (once I figured out WHERE to enter it) and used the suggested setting to change the size. However, this only seemed to alter the size of the icons, but did not affect the size of the text in the Menu and Toolbars or the Address bar. Is there a similar setting that affects the size of the text in the Menu, Tool, and Address bars?

The layout.css.devPixelsPerPx preference is a scaling or zoom factor, so it should affect everything in Firefox proportionally. It's possible that there are steps where the change isn't noticeable, but 1.5 (150% of 96 pixels per inch) or 2 (200% of 96 pixels per inch) definitely should cause a noticeable change to the text, too.

You can use code in userChrome.css to modify the font size of the location bar and search bar.

Add code to the userChrome.css file below the default @namespace line.

• http://kb.mozillazine.org/userChrome.css

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

#navigator-toolbox *, .findbar-container, #statuspanel-label {font-size:12pt !important;}

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

As you are on Linux - also see :

http://forums.mozillazine.org/viewtopic.php?f=38&t=3039060

and :

https://www.reddit.com/r/firefox/comments/96v9gx/increasing_the_bookmark_bar_icon_text_and_general/

I want to use the userChrome.css file to make the Firefox chrome font bigger, especially the status bar at the bottom of the window (shows URL when hovering). I've tried the solution on this thread and others, but i can't get it to work. It does not have any effect.

I created a css file per instructions and put it on my Mac in the only directory called chrome that there is: ~/Library/Application Support/Firefox/Profiles/ufnff1rd.default-release/storage/permanent/chrome

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

1. navigator-toolbox *, .findbar-container, #statuspanel-label {font-size:20pt !important;}

Am running firefox 68.0.2 and macOS 10.14.

What am i doing wrong?

P.S. disregard the "1." in front of #navigator. Somehow the forum sw added it.

Hi Ayrehead, first, about the folder, you need to create your own folder in the correct location. Please see:

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

Does the rule work if you put the file there?

The very wrong folder. Read instructions once again:

1. Open your currently active profile folder
2. Create a new folder named chrome

Also make sure that userChrome.css is a plain text file and not a file with rich text formatting (RTF) code.

It's working good now. I found the right place to make the directory to put the file in, directly under one of the profiles. Thanks for your help.

cor-el 's solution with the userChrome.css file worked perfectly on my Mac running Mojave 10.14.6 and Thunderbird 68.1.1. It took me a little while to figure out how to generate the .css file. This set of instructions from jscher2000 above was the most helpful: https://www.userchrome.org/how-create-userchrome-css.html

Thanks all for the useful information. I am new to Thunderbird and in LOVE with it.

The layout.css.devPixelsPerPx solution DID NOT work on my Mac. Not sure if it was a User (me) error or just not for Macs.