How to make mobile version if you have already used non-responsive for bootstrap?

Question

HTML

Hey! Please share your idea - I made several pages for the desktop, I used non-responsive from bootstrap / for bootstrap - everything is good. I used it because it was necessary to get rid of the "rubbery" and the grid and other bells and whistles of the framework were needed. Now there is a need to make a mobile version with a resolution of 320 to 480px. Naturally, the grid is not rebuilt, as it is disabled. Rebuild the elements that are inside col-xs-12 - no problem, what about the columns from which you need to make one long block and rebuild the elements in it? For example, there were three columns col-xs-2 col-xs-4 col-xs-6 and you need to do col-xs-12. Make additional separate blocks for the mobile version and hide/show them?? Tell me who can please.