As far as I know there are no resent modern skin templates for XC. XC stock ones are very outdated. All 3rd party ones are also 2-3 years old. You can check TheXCartStore, yBizz , maybe they are close to what you are looking for
http://www.thexcartstore.com/
http://www.ybizz.com/products/x-cart-templates.html
There are no XC html5/css3 templates at all anywhere... unless you have someone put one together for you from scratch...