You'll have to be more specific about "opened in browsers." Are you talking about opening your game in a mobile browser or desktop browser? When you say "in mobile devices"are you referring to an app version of your game?
Generally speaking though, we don't manipulate the files you upload to us in any way. We present them as-is in an iframe. On Android devices we launch games using the fullscreen API. On iOS we just maximize the frame over the viewport. Maybe that will help you in your debugging.