User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.2 Safari/605.1.15

Steps to reproduce:

I am developing a <p>-flowing, <div>-namespace-boxed programming language, and have been dismayed to encounter a sequence of FireFox eccentricities that disable my language in that browser, my favorite.

The latest eccentricity is that FireFox does not implement "width: fit-content", despite MDN's documentation to the contrary. That styling is crucial to the clarity and elegance of my computational flow, and I don't want to advise my users not to use FireFox.

See for yourself: try the attached YetAnotherTest.html in other browsers. It will work properly in Safari, Chrome, Edge; but not in FireFox.

Gary