Implement a new style for the website page

There is a visually quite simple and technically complex mobile version of the website page. On that side, there is code + several screens that change according to user actions. In some places, they change interactively, show statuses, respond to user actions, and more. The page switches (refreshes) itself according to the situation. The goal of the page is to receive answers to questions from an online quiz that is happening in real time. Everything is optimized to work quickly and not overload resources, meaning it should remain that way. The screens and statuses of the page are mainly made in the code, and a small part is separately included in the CSS, although it is present. The site is live, has been working for many years, is available online, and there is a separate dev version on a test server for making changes and testing.

The layout designer has already created a new style for the page, including screens and statuses. It all looks like an archive of screen and function files: CSS, images, JS, and HTML. Additionally, there is a project in Figma.

It is necessary to take this new skin and implement it into the existing site while preserving all functionality, but with a new appearance. If needed, move some parts of the functionality from the code to the CSS. If something is missing, provide a technical task for the layout designer, and he will finish it. Write what we need from our programmer in terms of access to the test version of the site. Optimize it to work as quickly as before, as the amount of resources and speed itself are important here. Our programmer cannot deal with the code or layout because he is busy with another project of ours, which is why we are looking for reinforcement. He can only suggest something specific because he wrote that code.

I am waiting for proposals!

Thank you.