Hi,
They are "100x100" thumbnails which are reduced using CSS in order to make the difference between the main image and the others.
I want to say that it is not my fault if your images does not have the same ratio.
What are you expecting me to do ?
Because the thumbnails have a the thumbnail size : 100x100...
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.