White border on Next Gen Pro Horizontal Filmstrip

Hi I am using your pro version, and in IE the horizontal filmstrip gallery shows a white background and border. I can’t figure out how to fix. I’ve tried adding an background colour to the iframe in css, but it doesn’t seem to work.

Example here:

http://www.dogwoodltd.ca/gallery/building-maintenance-gallery/

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