We use Firefox for Android in a project where users operate a web application. We would like to use Firefox in full-screen mode so that users can not see the UI and switch to other web pages. We would like to copy the necessary settings/files within the Firefox-APK to the devices. We have no influence on the source code of the web application. Does Firefox for Android support the userChrome.css file? If so, how do we add the userChrome.css to the APK file? If not, can the Firefox-UI be hidden by another CSS file (for example "browser.css" which is already included in the APK file)? Is there any other way to hide the UI? If necessary, we would also change the source code and create a customized Firefox-version. We downloaded the Firefox source code and are able to build the Firefox-APK. Best regards Thomas