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How can I change the font color and size of closed captions?

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  • Last reply by cor-el

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I have discovered that I prefer closed captions with the letters in yellow rather than white. How can I make this change in Firefox on a computer with the Windows OS. Also, I would like bigger closed captions.

I have discovered that I prefer closed captions with the letters in yellow rather than white. How can I make this change in Firefox on a computer with the Windows OS. Also, I would like bigger closed captions.

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You can use CSS code in userContent.css to set the text and background colors of the VTT caption text.

Add CSS code to the userContent.css file in the chrome folder in the Firefox profile folder.


::cue {
  background-color: black !important;
  color: yellow !important;
}

It is not that difficult to create userContent.css if you have never used it.

The first step is to open the "Help -> Troubleshooting Information" page and find the button to access the profile folder with the random name (xxxxxxxx.default-release).

You can find the button to go to the profile folder under the "Application Basics" section as "Profile Folder -> Open Folder". If you click this button then you open the profile folder in the Windows File Explorer. You need to create a folder with the name chrome in the profile folder with the random name (name is all lowercase). In the chrome folder you need to create a plain text file with the name userContent.css (name is case sensitive). In this userContent.css text file you paste the text posted. On Mac you can use the TextEdit utility to create the userContent.css file as a plain text file.

In Windows saving the file is usually the only time things get more complicated because Windows can silently add a .txt file extension and you end up with a file named userContent.css.txt. To avoid this you need to make sure to select "All files" in the dialog to save the file in the text editor using "Save File as".

You need to close (Quit/Exit) and restart Firefox when you create or modify the userContent.css file.

More info about userChrome.css/userContent.css in case you are not familiar: *https://www.userchrome.org/what-is-userchrome-css.html

In Firefox 69 and later you need to set this pref to true on the about:config page to enable userChrome.css and userContent.css in the chrome folder.