So I wanted to test the stacking context and grouping effects of offset-path, so I thought I'd look for a value of offset-path that: (a) was supported in Firefox and Chrome and (b) didn't cause the element to move at all. (The goal was a row in dbaron.org/css/test/2018/sta… .)

It turned out interoperability of CSS Motion Path (drafts.fxtf.org/motion-1/) is not very good... and I couldn't actually find a value that did what I wanted without falling back to a degenerate path ("M 0 0").

Some of the things I tried are in the demo at dbaron.org/css/test/2021/off… . Interoperability is not good... and wpt.fyi/results/css/motion?l… doesn't have very many tests.