Just curious can we use this in WordPress sites?

[ideepakmathur]

I'm trying to understand how I can use it in WordPress sites.

[dryabov]

@ideepakmathur I don't know of any free performance optimization plugins that support CLI tools to optimize CSS, but at least PageSpeed Ninja Pro does (you can watch the https://wordpress.org/plugins/search/csso/ page to find out when other plugins will be listed there).

An alternative to the CLI could be to run CSSO directly in the browser, but this would be a kind of manual optimization, so it is unlikely that this approach will be used in any plugin.