Build an Online Store

i am creating my online store on [login to view URL] platform. The site by default does not give options of adding filters to refine the products further. I need to get it done by creating a designer plugin. This is my current store(not fully developed as I am only evaluating) [login to view URL] I like all the aspects of this store except this. I need a solution for this problem. Now while creating solution, please keep in mind that the above store is fully mobile optimised(open it in your smartphone). I dont want any compromise with that. So it should work in mobile also equally well. You can check this site [login to view URL] . filters work on mobile as well as normal browser.