SASS, LESS, CSS without JavaScript in Polymer 3 with Webpack

Too Long; Didn't Read

Ever since the beginning, you’d had to write or inject your CSS into <a href="https://hackernoon.com/tagged/html" target="_blank">HTML</a>, in order to style Polymer Components. At a time, Polymer did include the ability to import <a href="https://www.polymer-project.org/2.0/docs/devguide/style-shadow-dom#external-stylesheets" target="_blank">external stylesheets</a>, although it was an experimental feature, and was deprecated in favor of style modules. With the recent version of Polymer 3, we ditch HTML (finally, no more silent errors 🎉!) in favor of good ol… er, I mean, good and new <a href="https://hackernoon.com/tagged/javascript" target="_blank">JavaScript</a> (ES2015 classes).