I have built responsive websites (same site is used on mobile phones, tablets, and laptops without changing codebase and is maintained with a single css file per function). This enables quick and scalable code to implement new functions. I firmly believe in the separation of front end code (html, javascript, css) and backend RESTful web services (php, java, etc). Although I have worked in several environments, the separation of this code makes for the most scalable website.