Mobile-first design

For years, the big buzzword of web design has been responsive--websites that look just as good when scaled from desktop to mobile size.

PWAs are, in essence, responsive design on steroids, expanding design for mobile to every aspect of the app, from appearance to functionality.

However, at the end of the day, we need to ensure that our app looks great on every screen size. It also needs to look good under the restrictions we've already discussed. We can't rely too much on big background images or intense graphics. We need a simple and good-looking UI, engineered for both looks and performance.