Responsive with NextGenGallery?

I am using the wunderslider to make my nextgen slideshows responsive. I have enabled the custom options but unfortunately the plug in is not giving the desired effect. Am I doing something wrong? I would like my slideshow to retain 100% width of the parent container and the height to remain proportional. If there is any other way of doing this I would be very happy to know.

http://newfiretrucksunlimited.davidreyburn.com/work-in-progress/golder-ranch-type-6-wildland/

Thanks

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