Deciem.com Type Website

I am looking to create a website like Deciem.com which is a portal website that features a single shopping cart, single customer account but has individual brands and domains for multiple brands with each brand having a unique visual style. I am looking to create this type of look for a website that will feature 2 brands for now and will in the future increase to 3 or 4 brands. My platform is currently Magento which allows shared cart, shared customer account across different websites, so all we need is unique themes and visuals for each brand. Once the website launches, then you will be hired for long-term support and upkeep and for future upgrades and updates.