Wp-dtree styling

Curious if anyone knows how to change the line height of the nodes (text)? I went into the style.css page and tried a few different ways but can’t seem to change anything. Even tried adding margin and padding to it but everything just overlapped. The lists in my sidebar are a bit more spread out than the default setting.

Any help would be appreciated.

http://wordpress.org/extend/plugins/wp-dtree-30/