Hi Leonard,
Yep you can modify the CSS by overriding the plugins CSS by placing a duplicate copy of events.css (wp-content/plugins/the-events-calendar/resources/events.css) in an ‘events’ folder in your theme.
Look for line 416 that should look like:
.eventsListWidget li, .singular.page li.hentry, .eventsAdvancedListWidget li, .singular.page li.hentry {
margin: 6px 0 !important;
padding: 0 0 10px 0 !important;
}
Just remove the !important rules like so:
.eventsListWidget li, .singular.page li.hentry, .eventsAdvancedListWidget li, .singular.page li.hentry {
margin: 6px 0;
padding: 0 0 10px 0;
}