Currently, all events are set min-height of 25px. That causes the visually improper display of events:

Removing the applied min-height style will make sure that the events are visually positioned as expected, but the events' titles will be partly or fully hidden:

A workaround based on custom CSS is demonstrated in the following example: 

https://stackblitz.com/edit/angular-bvh7fq-1s3ub7