Removing Vertical Margin/Padding between image widgets

Hi all,

I’ve searched for an answer, so I apologize if I missed something.

As best I can, I’m trying to re-create the our site’s sidebar-navigation on its blog.* Unfortunately, I can’t figure out how to adjust the margin/padding between widgets so that they’re reasonably spaced.

I’m uncertain whether the relevant formatting lies in the theme’s php, its css or, this widget. Help would be much appreciated.

Screenshot of the blog here; the rest of the site (which is how I want the blog to look), here.

* I’ve no concern about the image-rollover issue.

http://wordpress.org/extend/plugins/image-widget/