Demo for possible sourcemaps issue with TailwindCSS

1. Clone repo
2. Run npm install
3. Run ./node_modules/gulp/bin/gulp.js to compile CSS and sourcemap

If you then open index.html in Chrome and inspect the blue button, you'll see some of the styles reference <input css 1> as the source instead of main.css. You'll also notice the sources array in main.css.map is: ["main.css","<input css 1>","<no source>"].