Hello,
A theme is an add-on that changes the visual appearance of Firefox. You can switch to another theme as follows:
- Click the menu button and choose Add-ons and themes.
- Switch to the Themes panel.
- The built-in default System, Light, Dark and Alpenglow themes will be listed, as well as any themes you installed yourself.
- Find the theme you want to use and click the Enable button.
To uninstall any themes you installed yourself, click the ellipsis (3-dot) icon and click the Remove button.
For more information about Firefox themes, see the articles Use themes to change the look of Firefox and Built-in themes in Firefox - alternative to complete themes.
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