Set Menu/Application Font Size in Firefox

After using a Windows 7 machine for a week or two I noticed that the font size of the menus of Firefox seems a little small. It turns out you can actually adjust the size of the application fonts in Firefox using CSS.



First, you need find the sample template for changing the Firefox UI, userChrome-example.css. This can be found in the following directory:

c:\Program Files\Mozilla Firefox\defaults\profile\chrome



First, copy userChrome-Example.css to userChrome.css.



Next, add a rule to set the default font size. For example, this sets the font size to 10pts:

* {
 font-size: 10pt !important;
 }

With the file created and rule added, copy userChrome.css to your profile directory for Firefox. This gets a little tricky as the AppData directory is hidden by default so you may need to actually type the name into Windows Explorer. So here is the path:

c:\Users\UserName\AppData\Roaming\Mozilla\Firefox\Profiles\someRandomeString.default\chrome



That is it. The font size for menu and other application text should now be set to 10 pts.