A theme is a simple type of Firefox add-on which allows you to customize your browser skin. This article describes how to find, install, and manage Firefox for Android themes.
Firefox for Android themes allow changing of color schemes and background images of the Firefox toolbars.
You can access the Android themes from the settings menu inside Firefox for Android:
To switch themes, follow the instructions for How to install Themes above and install another theme.
If you want to go back to the default Firefox for Android theme, uninstall the current theme add-on: