CSS Update and Optimization of my website homepage

I would like to change the central part of my homepage from actual www.neveitalia.it to the following:
https://www.neveitalia.it/test/2024/desktop.html
https://www.neveitalia.it/test/2024/mobile.html

PSD available.
DEV environment available.
Only edit css and if necessary change the html markup
Keep existing html/css breakpoint

(Optimization the CSS of the whole site will be a new project, which I would like to follow preferably with the developer who will edit this new homepage)