Do not add "close notification" button for etherpad >= 1.8.3
We can identify etherpad 1.8.3 by checking the flex-layout class, which was an important step of 1.8.3 and will not be removed
We can identify etherpad 1.8.3 by checking the flex-layout class, which was an important step of 1.8.3 and will not be removed