Mobile compatibility

I’m a new user here and recently created a fronted app with firebase studio to index into google with hyperlinks to redirect it to a older website where all the payment methods and checkouts are stored. However, I used Firebase Studio due to its AI Compatibility which is essential for people like me. It’s not perfect but I got it to work and finished the app however whenever I visit it on mobile the site becomes crazy with overlapping images, text etc. Is there a way to fix this? to separately design a mobile version.