Mod CSS for /themes-ai1ec/vortex

I am trying to mod the css for /httpdocs/wp-content/plugins/all-in-one-event-calendar.1.10.5/all-in-one-event-calendar/themes-ai1ec/vortex however any changes I make are never reflected on the site.

I am specifically trying to add some margin/padding below the calendar because it is too close to the bottom of the pg. Because there is no shortcode I can’t add anything below it to make this happen. I can easily add a paragraph or two above the calendar but can’t quite figure out how to do this below.

https://e-trainu.com/training-schedule/