Tools and technologies come and go, but one thing has remained constant for me over the past decade: progressive enhancement.
Progressive enhancement isn’t a technology. It’s more like a way of thinking. Instead of thinking about the specifics of how a finished website might look, progressive enhancement encourages you to think about the fundamental meaning of what the website is providing. So instead of thinking of a website in terms of its ideal state in a modern browser on a nice widescreen device, progressive enhancement allows you to think about the core functionality in a more abstract way.