Sass(.scss)
http://sass-lang.com/documentation/file.SASS_REFERENCE.html#using_sass
http://beautifytools.com/css-to-scss-converter.php
https://gist.github.com/xgqfrms-GitHub/1086b2d97368baf71be7f37d71caebb5
https://gist.github.com/xgqfrms-GitHub/f22f0e4502f93630b66ac9d43f6a6069
webpack 2 scss to css
https://github.com/webpack-contrib/extract-text-webpack-plugin/issues/263