[Lynne]

Well, two things.... the size is set by your body tag which is setting the font at 13px. And, the extra spacing is set here:

#wgo_onlineusers .commalist li {
  display:inline-block;
  margin-left:1px;
}

So, try something like this in the additional.css template:

#wgo_onlineusers .commalist li {
  font-size: 11px;
  margin:0;
}