I’m sorry you’re hitting up against difficulties.
There’s something strange about the structure of your theme and it’s CSS that is getting in the way here (if you flip to a default theme such as Twenty Fifteen I feel confident you will not experience the same problem).
As a possible easy fix, can you visit Events → Settings → Display and try adjusting the default template setting? Right now you seem to be using the Default Events Template – but does switching to the Default Page Template (and you might try any other options listed there) resolve this?