postcss-preset-env transform for sheetify. Use tomorrow's CSS syntax, today.
$ npm install sheetify-cssnextconstsheetify=require('sheetify/stream')constpath=require('path')constopts={transform: [['sheetify-cssnext',{sourcemap: false}]],basedir: __dirname}sheetify(path.join(__dirname,'index.css'),opts).pipe(process.stdout)