need of an oscommerce 2.2 mobile layout for my site

I have an already working site made in oscommerce 2.2, for desktop it works perfectly but don't have mobile layout. I need a mobile layout of this site without change desktop layout. So the desktop users will continue to navigate with the current working desktop site and the mobile users will navigate with the new mobile version. In my google search consolle actaully i have 98% good url for desktop and 0% for mobile. I need that also mobile url must have 98% of good url.