Cannot Scale Portrait image

I love this carousel, added some custom CSS to fit my site and everythign works fine, except portrait images are scaling to the full width of the carousel, thus keeping their full height and off setting everything.

Does anyone know how I can fix this?

find the gallery here:

http://schrodingersgallery.co.uk/writing/carly-cuarnute/#FelixPhillips_1

I would recommend this to anyone

https://wordpress.org/plugins/owl-carousel/