product page with html css js(no framework). No mobile design(for now)

That was quite challenging! I am looking forward to go for the full e-commerce version in the future. I need help for the mobile design, it seems totally different than the desktop one, how can you do it? I would also need some tips for the Javascript on how to handle all these different things (cart handling while upgrading the html content etc etc): is there any kind of pattern or strategy I should follow? Should I go for a framework in the future? Should I also use Docker and Kubernetes for a real e-commerce or are there any tips you'd give me? Thanks a lot in advance. Happy coding to you all!