Nextgen Pro Slideshow and white backgrounds

I set up a Pro slideshow with all images at 600px on the wide side and the Slideshow also formatted to 600px. I’m getting a fat white background border and don’t know how to get rid of it. Here’s the page, a work-in-progress.

Thanks for any assistance!

http://kentannenbaum.com/black-blue/

https://wordpress.org/plugins/nextgen-gallery/