Adaptation of the site layout for mobile devices

There is a ready layout of pages (HTML/CSS/JS). It needs to be carefully modified and adapted to different screens: phone, tablet and desktop. Now on mobile devices, blocks move, the grid breaks in places, the header and menu behave unstable, buttons and input fields sometimes go beyond the container.

Need to get everything back to normal without a complete rewrite: tweak styles, media queries, indents, alignment so pages look equally neat in Chrome/Safari. Also check that clickable elements do not overlap and that horizontal scrolling does not appear.

I will give the files in the archive or give access to the repository. We need clean code and that nothing breaks on the desktop after editing. If somewhere it is easier to solve through minimal changes in HTML, it is ok, but without changing the structure of the pages radically.

It is desirable to do it quickly, at the exit I want to receive updated files and a short comment on what exactly was fixed.