Hi,
That's normal. The elements are not responsive.
There are two ways to make them responsive:
1. You turn on the "use bootstrap design" setting of the hikashop configuration but this can only work if your template is compatible with bootstrap 2, and looking at your pages, it doesn't seem to be the case, so that won't work.
2. You add custom CSS to your template in order to make these elements responsive. To do that, you can use @media CSS queries in the frontend CSS file of HikaShop.
For example, for your product page, you can add such CSS:
@media (max-width: 780px) {
#hikashop_product_left_part, #hikashop_product_right_part{ width: 100% !important; }
}
How to add that CSS to your template will depend on your template so it's best to ask them but here is a generic tutorial:
www.htmlgoodies.com/beyond/webmaster/too...h-css-in-joomla.html