Hi,
The link to your store does not allow us to see the content ; it is password protected.
If you're using Joomla 3 with a template compatible with "Bootstrap 2" ; you can activate the "Bootstrap Design" in your HikaShop configuration in order to get a responsive rendering for the HikaShop part.
But all the display issues can't be link to HikaShop ; it is also dealing with the template ; both have to "work together".
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.