How to eliminate white space gap between sub-category in widget

Hi

I've been using Geocraft widget category to show all listing category at my front page (using hierarchy selection). But when im start adding sub-category, i realized that between the sub-category in widget, there's a significant gap white space. How do i eliminate these white space gap? so my sub-category looks close to each other, rather than separated by these white gap. Thank you

note : i'm look at the widget.php files, but not sure which code should i edit. so i made a screenshot for references. Thank you

Iqbal