Note that there's slightly more choice here than just that: 1px may be either (1 physical real-world inch on the output medium)/96 or set related to the referen

Note that there's slightly more choice here than just that: 1px may be either (1 physical real-world inch on the output medium)/96 or set related to the reference pixel. (Though in CSS 1in always equals 96px, etc.) (See https://drafts.csswg.org/css-values-4/#absolute-lengths https://drafts.csswg.org/css-values-4/#absolute-lengths)