Styles based on css variables not working

[anfield]

Hi

I have a setup/config issue which seems to be preventing any styles basecd on css variables from being found. PrimeFlex is working generally, but if I use, for example, bg-blue-900, the browser inspector reports 'var(--blue-900) is not defined'.

I've tried using both CDN <link rel="stylesheet" href="https://unpkg.com/primeflex@3.1.2/primeflex.css"> and NPM installation with the same result.

I'm using:
PrimeFaces 11
JDK8
IntelliJ IDEA with SCSS file watcher

Thanks

Matt