Customize your Firefox browser
Firefox themes let you change your browser’s appearance. They set the color scheme for browser menus and Firefox system pages, and can even add a background image to your Firefox toolbar.
Firefox comes with a default system theme and is preloaded with light, dark and colorful variations.
You can find more free custom themes at addons.mozilla.org. Browse the top-rated, trending and most recommended themes. Or look for themes by category, including music, seasonal, sports, and nature. Tailor your experience to your tastes. Cute critters, evil robots, beautiful landscapes — there are thousands of options to make Firefox your own.