Theme Font & Size Changer

Theme Font & Size Changer Project Image

Congratulations! Theme Font & Size Changer installed successfully. You can right now start using your new add-on.

Theme Font & Size Changer is a simple browser tool that lets you change the font size and font family of Firefox. It is especially valuable tool for visually impaired people and wide screen users.

There are three places that you can manage the global font size and font family of Firefox via Theme Font & Size Changer. Add-on Bar icon, toolbar button and Tools menu option. All font size and font family changes are instantly applied and they are saved permanently and through sessions.

Different from add-ons that enlarge and reduce text on web pages, Theme Font & Size Changer changes the font size and font family in all windows, menus, toolbars, etc within Firefox itself.

It was initially created to be an accessibility aid for persons with visual impairments and for those without perfect eyesight, but it’s also useful for Firefox users with high monitor resolution settings and wide screens.

While Theme Font & Size Changer was written to be used with Firefox default theme, it does work with other non-default themes, but you may come across issues where some elements within Firefox retain the (non-default) font size setting that the theme developer chose for their theme.

There are three places that you can manage the global font size and font family of Firefox via Theme Font & Size Changer:

• Add-on Bar Button: Click on the Theme Font & Size Changer button to open up Theme Font & Size Changer settings panel.

NOTE: Add-on Bar resides at the bottom of the Firefox window. Add-on Bar is the old status-bar. If Add-on Bar is not visible, you should activate it. To do so, choose View menu from Firefox Menu Bar and hover over the Toolbars option and click on the Add-on Bar option if there is no tick. If you are Windows 7 user, you should click on the orange Firefox button at the top of the window and hover over the Options and click on the Add-on Bar option if there is no tick.

• Tools Option: Choose Tools menu from Firefox Menu Bar and click on the Theme Font & Size Changer option. It will open up Theme Font & Size Changer settings panel.

• Toolbar Button: It is optional so it is not visible as default. If you want to place a Toolbar Button, right click on a toolbar button like Home Button, then choose Customise option. A window will pop up. Find the Theme Font & Size Changer button, then click and drag the Theme Font & Size Changer button in the toolbar of your choice and drop the button. Clicking on this Theme Font & Size Changer button will open up Theme Font & Size Changer settings panel.

In Theme Font & Size Changer settings panel, Font section provides fonts currently installed on your operating system. With this option set, you will be able to fine tune your font family of Firefox theme.

In Size section, simply select a font size value (from 6 to 80 pixels) and the changes will be applied instantly and globally.

A Normal (default) value is also provided as well as an indicator next to the currently applied font size and font family setting so that you can reset to the default Firefox values.

Known Issues:
Please keep in mind that this extension was designed for use with default theme of Firefox and the fact that it works with non-default ones is more of a bonus than the primary goal and function of it.

Compatibility issues found when tested with 32 Firefox themes were minor overall, but a few were major, while others had no compatibility issues at all.

Any compatibility issues will mostly be dependent on the theme (or extension) developer’s CSS value choices for any given element.

The font size in some elements in non-default themes remains unchanged.

For example and through testing, the font size of tab text was unchanged by Theme Font & Size Changer (in some themes).

Repeating backgrounds:
With some non-default themes you may encounter repeating backgrounds (on toolbars, etc) when the font size is increased. Increasing the font size also increases the height of other elements (like toolbars) and so if specific CSS properties are not set to prevent backgrounds from repeating, then a background will repeat itself which you may find to be undesirable.

Text bleeding out of elements or being cut off:
You may notice this in some themes such as on dialog buttons, drop down menus, and tabs.

No known compatibility issues with the following themes:

NASA Night Launch
Kempelton Large
Mostly Crystal
Walnut for Firefox
Ambient Fox Xyan
Themes by Aaron Spuler

There are no known compatibility issues with Personas skins.

Special thanks to Ken Saunders for the priceless contribution and testing efforts.

If you find the application useful please support my development efforts.

77 Responses to “Theme Font & Size Changer”
  1. Eric S says:

    this is super lovely……like good looking thangs!!!!!

  2. ladiss says:

    Thank you. Very good extension.

  3. cheryl says:

    Thanks for the fantastic add-on it is a welcome change!

  4. Yvonne says:

    Wauw, many thanks for this great add-on.



    THANK YOU SO MUCH FOR THIS ADD-ON. Again thanks for the effort. Hoping to see more add-ons like these in the future.

  6. agus says:

    Thank you for this excellent add-on! Coming from Ubuntu and Linux Mint where one is spoilt with crisp, clear fonts on Firefox and Thunderbird, I was very disappointed after I recently installed these apps on my new Mac mini. However, with the help of your add-on, FF and TB now look good on the Mac, too!

  7. agus says:

    Thank you for this excellent add-on!

  8. thank you, you have make my cyber life so great!.. go..go..goooooo..

  9. Begoneh says:

    Thank you so much for this simple and easy to use add on. It works brilliantly without causing any problems. Wonderful job.

  10. wiDsuge says:

    thanks for this great add ons,,

  11. Shayna says:

    Thank you SO MUCH for this. Now I can finally see the tool bar. Discovered it after Firefox 29 trashed my settings and I had to start all over again. The fabulous benefit was that I found your Theme & Font Changer when trying to repair everything.

  12. Mike I. says:

    Please ignore and delete my last question.

    Theme and Font Size Changer works GREAT! I don’t know what I was doing before, but when I activated it from the status bar, all the options were there and work perfectly.

    I only wish I had found your add-on before spending at least an hour trying to change Thunderbird’s font.

    Thank you so, so much!!!

  13. Asrael Astrum says:

    User interface=Optimized…

  14. cmcanulty says:

    thanks I really need this for the larger fonts and the new enable context menus really made it perfect!

  15. I advise everyone!
    Everything is comfortable and beautiful!

  16. this Firefox is easy to use and very useful

  17. Geoff Ingram says:

    Thanks Baris, the new version (8.6) fixes the problem I was experiencing under SeaMonkey.
    Thank you for this useful add-on.