I'm not familiar with modern Sass. Has it evolved much in the last decade? I'm still using Less because I installed it 10 years ago and it still works great, but there's almost 0 features that haven't been adopted into CSS now so I really don't need at all.

There is 1 I guess. I wrote a loop somewhat recently because there doesn't appear to be a variable for DPI yet. `env(dpi)` doesn't exist or I could have did what I wanted: scale a <canvas> element to be 1.0 scaling regardless of the user's screen scaling.

Have you tried https://open-props.style/ ? Atomic CSS but leverages good CSS principles.