natours is a sample page written with plain html and sass (from udemy advanced-css-and-sass Jonas Schmedtmann course).
Check it out at https://johncol.github.io/css-course-natours/
To install packages, in a command line run
npm install
Then run
npm run start
Which will trigger a compile sass task and a live-reload server at port 8080.
Now you can write your sass rules, and it will automatically write the corresponding css and reload the browser tab to see the latest changes.
Run
npm run build:css
This will compile your sass code, concatenate it with the font styles file, auto-prefix it and minify it.