The event window out of the site

Hi! There was a problem displaying the calendar at 100% of the screen size. When focus on an event, it is displayed outside the boundaries of the site, thus a scroll bar appears and, accordingly, the user does not see the event. The problem is especially important on mobile and tablet devices. This problem only occurs with events that take more than a week. How to fix it? Screenshots I enclose.

https://cdn1.savepice.ru/uploads/2017/8/4/829388b243b6a880e94c4444aa5f33ea-full.png
https://cdn1.savepice.ru/uploads/2017/8/4/2fd1b3b465723c12579bb6d4f8a46612-full.png