hugo/docs/content/en/hugo-pipes/minification.md

title	description	date	publishdate	lastmod	categories	keywords	menu	weight	sections_weight	draft
Asset minification	Hugo Pipes allows the minification of any CSS, JS, JSON, HTML, SVG or XML resource.	2018-07-14	2018-07-14	2018-07-14	asset management		docs parent weight pipes 50	50	50	false

Any resource of the aforementioned types can be minifed using resources.Minify which takes for argument the resource object.

{{ $css := resources.Get "css/main.css" }}
{{ $style := $css | resources.Minify }}

Note that you can also minify the final HTML output to /public by running hugo --minify.