The MDN Web Docs state that the following are all valid properties:
transform-box: content-box;
transform-box: border-box;
transform-box: fill-box;
transform-box: stroke-box;
transform-box: view-box;
It also states that all current (November 2021) browsers have full support, except IE11 of course. Caniuse.com confirms this browser support for transform-box.
However, when I attempt to use transform-box: content-box;, transform-box: border-box; or transform-box: stroke-box;, Chrome Dev Tools reports these as "invalid property values":
Am I missing something?