To generate the CSS during development after any changes to that file, you must run:which generates the final CSS file:
npm run sassmain.cssYou then need to explicitly include that where
main.css file in your --template. For example, our ourbigbook.liquid.html contains a line:<link rel="stylesheet" type="text/css" href="{{ root_relpath }}main.css">root_relpath is explained under Section "--template".