Use purgecss to remove unused css

my postcss configuration:

const purgecss = require("@fullhuman/postcss-purgecss")({
  content: [
    "./app/**/*.html.erb",
    "./app/helpers/**/*.rb",
    "./app/javascript/**/*.js",
    "./app/assets/javascripts/**/*.js",
  ],
  defaultExtractor: (content) => {
    const broadMatches = content.match(/[^<>"'`\s]*[^<>"'`\s:]/g) || [];
    const innerMatches = content.match(/[^<>"'`\s.()]*[^<>"'`\s.():]/g) || [];
    return broadMatches.concat(innerMatches);
  },
});

module.exports = {
  plugins: [
    require("postcss-import"),
    require("tailwindcss/nesting"),
    require("tailwindcss"),
    require("autoprefixer"),
    ...(process.env.NODE_ENV === "production" ? [purgecss] : []),
  ],
};