Tooltip on Hover not working

Hello there,

I am not an expert, so I may have got this wrong, but I would like for the event title of my calendar to either be displayed in full length, or the event title at least to be displayed on hover as a tooltip (I believe this should be working, but it isn´t?).

If someone could point me in the right direction to solve this then I would be very grateful. Thank you!

The page I need help with: [log in to see the link]