Adobe XD is part of their creative cloud offering and they publish themes and videos about the design process. It is really easy to mockup a real looking web pa

Adobe XD is part of their creative cloud offering and they publish themes and videos about the design process. It is really easy to mockup a real looking web page in XD, then use a favorite CSS framework to create it. Also themeforest.net is great too, pharaohgeek mentioned that already, but that is also a great starting point as good themes look more like bootstrap documentation to give you a huge head start versus from scratch.