Hello,
I don't know from which HikaShop version you make your update, but you have to know that when you create a frontend customization, while an update with new html structure this custom css will be kept, and unfortunately can leads to this.
Anyway, I have your solution, you have to update your frontend file css, see my screenshot :
Around
line 134, before you have this :
.hikashop_product_left_part {
text-align: center;
float: left;
width: 50%;
}
Change the
width command for
100%.
Hope this will help you to solve your issue.
Regards