Hi Glenn,
To do this just target the category classes attached to the li elements of the widget by adding something like the following to your theme’s style.css file:
.eventsAdvancedListWidget .cat_community-event {
background: #e7e7e7;
}
Replace ‘community-event’ with whatever the name of your event category assigned to the event is.
Here’s a screenshot of the HTML showing the classes added to an event: http://cl.ly/image/1W450u1d372g – depending on which web browser you use you can utilize various methods for viewing the HTML by clicking or selecting an element on the page and viewing it’s markup and CSS.
Does that help?
– Jonah