[Plugin: Events Calendar] Clash with drop-down menu

Hello, I wonder whether anyone else has run into this problem.

As soon as I installed the events calendar, it made my drop-down navigation quit working. I took a quick look to see whether there were new styles with the same name as my drop-down styles, but didn’t see any. So I uninstalled and went with another calendar.

Any ideas?

https://www.ads-software.com/extend/plugins/events-calendar/