site not is responsive with monitor resolution, with monitor resolution low, if you opena a chat, you can't close, dont have a X for close. for other otpion, all ok
You can click on the right, "whited-out" part of the screen to return to the main screen, and also on the same "tab" that brought you there.
You can also swipe left if you're on mobile.
Being responsive on every screen size has actually been a big part of the development
http://i.imgur.com/Ur0rWsI.png