[Plugin: NextGEN Gallery] Gaps between thumbnail images

I have just installed the NextGen Gallery using the Striking theme from Kaptinlin. I have noticed when trying to view a gallery on one of my pages the thumbnails have large gaps of space above and below the images. Please see attached image here: http://postimage.org/image/94t731uy9/

I have tried editing the style sheets, but nothing seems to change no matter if I change border, padding, height, width on any of the settings. Does anyone know how to fix this issue? I obviously would like the images to be closing together and line up more properly in rows.

Thanks.

http://wordpress.org/extend/plugins/nextgen-gallery/