Calendar showing all events on top of each other

The calendar shows all the events on top of the calendar. Thus you see only half of it. This is happening in Chrome and Firefox, but not in Safari.
You see all events descriptions in separate window with the X at corner, but they cannot be closed by clicking on it. I managed to hide them in the CSS:
.details.no-image {
display: none;
}
However, now it’s not possible to see any event details. Can you help me fix it?

https://wordpress.org/plugins/my-calendar/