RWDt
RWDt is a term that can refer to several different concepts, depending on the context. One common interpretation is that it is an abbreviation for "responsive web design" followed by "technology." Responsive web design is an approach to web design that makes web pages render well on a variety of devices and window or screen sizes, from minimum to maximum display size. This is achieved through a combination of flexible grids, flexible images, and media queries. The goal of RWDt in this sense would be the implementation and application of these technologies to ensure a consistent and optimal user experience across desktops, tablets, and mobile phones.
Another possibility is that RWDt is a specific, though not widely recognized, company, project, or product name.