Mobile display - category listing

-- HikaShop version -- : 2.4.0
-- Joomla version -- : 3.4.1

Hi,
I have two websites that I manage: morenadancewear.com.au, and salsashoes.com.au.
when displaying a category of products (refer to the link above), it seems to be all working well on a normal browser. However, when I try to open this webpage in a mobile phone (iPhone for example or using MobileTest.me website), it seems that the products overlapping each other and not forming a horizontal line as in the salsashoes.com.au website (link: salsashoes.com.au/hikashop-menu-for-prod...ies-salsa-shoes.html ). I thought first it could be because of the template but this behavior persists with different templates.
Any idea or solution to this problem.
regards,
Khaled