Workbox is a set of libraries and Node modules that make it easy to cache assets and take full advantage of features used to build Progressive Web Apps.
You may also be interested in ...
Beercss
Build material design in record time without stress for devs.
Quick and Easy Dark Mode with CSS Custom Properties
Giving users a dark theme option can be beneficial for accessibility, as some people experience headaches or visual difficulties from excessively bright screens, or have trouble reading for long periods on a light background. Post written by Michelle Barker.
Prepros
Compile Sass, Less, Stylus, Jade, CoffeeScript on Mac, Windows & Linux with Live Browser Reload.