Distorded product size image in product gallery

I’m building a webshop using woo commerce and everything is going fine
My website (www.4x4sintannalandnl/webshop) is coming along, however there’s something wrong withe product images a soon as I upload multiple images to a product as can been seen here:

http://www.4x4sintannaland.nl/webshop/?product_cat=tred

When viewed in grid mode, there’s no problem, but when I use the ” list view’ the images become distorted. When I only use the feature image (so 1 image per product) everything is fine.

The single product page looks good:
http://www.4x4sintannaland.nl/webshop/?product=tred-1100-4×4-rijplaten-zandplaten

https://wordpress.org/plugins/woocommerce/