[Dylan16807]

> cm/in as your unit (which is actually also what px is based off of in the web, not physical pixels)? ° doesn't make sense until

Nope!

A CSS pixel is 96 DPI at 28 inches from the viewer.

px is fundamentally angle-based. 1/47 of a degree. And sure it's a "scaled value of cm" at some point but this way the scaling is more obviously handled on a per-device basis.