Responsive design is everywhere. We are living in an age where a single webapp can be used across a multitude of devices; each with their own resolution and screen size.
If that wasn’t overwhelming enough, rarely is a single UI effective on every type of screen: Mobile devices excel at displaying content stacked vertically, while laptops and desktops’ extra screen real estate prefers content that sprawls out horizontally. Tablets are roughly a mixture of the two, depending on their size. And we can’t leave out the users that browse in landscape orientation (I know you exist!).
That is a lot…
