If you change system UI zoom setting then the 1 pixel size in the browser change with zoom. At 200% web 1px is actual 2px. I am not sure how it could be "1/96th of an inch" when it can change size depend on the system setting.
Don't take my word for it, it's how it's defined in the CSS spec: https://www.w3.org/TR/css-values-3/#absolute-lengths