Image stretched disproportionately in mobile device

-- url of the page with the problem -- : www.daniellefenningdesigns.com
-- HikaShop version -- : 4.0.1
-- Joomla version -- : 3.9.1
-- PHP version -- : 3.4.9
-- Browser(s) name and version -- : smartphone

When a visitor is using their mobile device and they click on the product image, the pop image is stretching disproportionately. It does not do this on the desktop. How do I fix this in the configuration? Thanks

found it in another post. Changed to Shadowbox external