[Theme: Ari] Dotted Line Seperating Widgets

There is a dotted line separating the widgets on the sidebar.
I would only like to have this dotted line on the bottom of a specific type of widget. How do I do this?

Here is the link to my website: http://www.payitforwardfriends.com

I would like to have the dotted line under every title (every title is a separate widget from the corresponding content for the title)

Thanks!

http://wordpress.org/extend/themes/ari/