Advanced CSS redesign existing Squarespace site

We need an existing Squarespace site already paid for redesigned with new content. The content on the existing site can be archived, deleted or whatever is easier. The following pages will be sufficient for our content. Home page our story our team service catalog security model contact page This is static content. No online booking, e-commerce etc needed. We are looking for some advanced CSS like the following example (see link below). We are hoping once it is built that we can add / modify pages as needed in the future. https://e-money.com/?ref=land-book.com