When using cast option from the device menu and open Firefox, only small part of the website is actually visible on the device screen itself (where device being cast to displays the whole page regularly). It does not depend on the website and is related only to Firefox. And last but not least, as described in some other issues https://support.mozilla.org/en-US/questions/1205338 https://support.mozilla.org/en-US/questions/1202682 https://support.mozilla.org/en-US/questions/1182866 Cast button does not appear as it should when not already casting (youtube as the prime example). OS: Android 8.0.0 Phone: Motorola Moto Z FF version: 59.0.2