Based on the official starter kit and come with 7 in 1 folder structure SCSS development using postcss, purgecss and cssnano.
"watch:sass": "sass --no-source-map --watch src/assets/scss:_site/assets/css",
"watch:eleventy": "eleventy --serve",
"build:sass": "sass --no-source-map src/assets/scss:_site/assets/css",
"build:eleventy": "eleventy",
"build:purge": "purgecss -c ./purgecss.config.js -o _site/assets/css/main.css",
"postbuild": "postcss _site/assets/css/*.css -r --no-map build:purge",
"start": "npm-run-all build:sass --parallel watch:*",
"build": "npm-run-all build:sass build:eleventy"
npm run start
npm run build
or, you can use any of the provided scripts to run the task you need.