I have no interest in doing so. IE has long lost my attention.
This doesn't change the fact that the polyfill *is* quite limited, period. There are factual limitations that prevent to reach 100% compatibility.
Please post updates to your library only when you have signficant changes.
And let viewers decide if a demo is "impressive" or not.
With regard to what the Polyfill can actually already do, I consider "quite" limited to be out of place.
And I think I know better what the factual limitations are.
With more effort, it is possible to pass almost all of the CSS-variables web platform tests.
Without even taking a close look at the polyfill, keep your criticism about the form of the post and not about the content.
Who told I haven't taken a closer look? I've even starred the repo *a long time ago*.
I stand by my position. I don't consider a limitation just what's implemented in the polyfill, which is actually quite good - but also the performance impact of the solution, and the outlook of the usefulness of it. Polyfilled custom properties can't be animated, for once; and generally a bit chunk of their actual convenience comes with Web Components and Shadow DOM (which can be shimmed with *severe* limitations in IE), and in the future with all the Houdini APIs.
To quote what Echo JS' mod tracker1 said 5 months ago: "Personally, I don't support any version of IE at this point. It's EOL, replaced and a security risk. Not to mention the shims/shivs/transforms needed for ES2017+ are massive. It's a target that's not worth taking for the most part."
In short: if I *have* to support IE, CSS Custom Properties are the least of my concerns. That doesn't change the fact that *any* polyfill for IE is a remarkable effort that deserves respect.
Also, my original comment *was* about the form of the post. It seems you took it quite personally and I don't know why.