Add Divider to Events Page

Our Events page lists all events past and future, which is what most of us would like to see.  I have a request to add a divider between the two because people get confused.  Many of our events are similar/identical and they miss the slash through the date in the image, which is the only noticeable difference.  I only have basic skills so I don't know if it's possible and, if so, how to go about it.  URL is www.spokumbent.com.  Thanks in advance.

You can use this to Website Tools > Custom CSS

/* line between upcoming - past events */
.eventlist.eventlist--upcoming {
    border-bottom: 5px solid green;
    padding-bottom: 50px;
}