NextGen Gallery Layout Issue

I’ve got NextGen Gallery on a photographers site, along with wpEstore and NextGen plugin.

Everything works except for gallerys where there are portrait and landscape images, see http://www.pixeldevelopment.co.uk/clivewasson/miscellaneous-gallery/?album=8&gallery=13

I’m assuming this is a CSS issue but I’ve tried a few things and its not working.

Any suggestions gratefully received as this is bugging the pants off me!