CSS Modules in depth
https://github.com/css-modules/css-modules
https://webpack.js.org/loaders/css-loader/#modules
in practice
https://www.gatsbyjs.org/docs/css-modules/
https://nervjs.github.io/taro/docs/css-modules
https://www.javascriptstuff.com/what-are-css-modules/
https://css-tricks.com/css-modules-part-1-need/
https://www.sitepoint.com/understanding-css-modules-methodology/
http://www.ruanyifeng.com/blog/2016/06/css_modules.html