hugo-theme-introduction/package.json

{
  "scripts": {
    "build": "npm install -g postcss postcss-cli autoprefixer && cd exampleSite && hugo --gc --minify -t ../.. -d ../docs -v -b https://hugo-introduction.netlify.app/",
    "dev": "cd exampleSite && ENVIRONMENT=development hugo -t ../.. server"
  },
  "devDependencies": {
    "autoprefixer": "^10.4.2",
    "postcss": "^8.4.6",
    "postcss-cli": "^9.1.0"
  }
}