Status of Ruby Text Offset?

It appears this topic was last discussed on February 7th of 2015 in the
thread "how to specify offset of ruby annotation box from ruby base box?"
where it was suggested that the "margin" style property on rb and rt tags
would be the best way to support ruby annotation text offset in the future.

I'm wondering if there has been any advancement on the topic? Either in
browser support or in a forthcoming recommendation for Ruby styling?

I did find that an annotation text offset could be achieved with the
"bottom" property set on an inner span tag of an rt tag.  But with very
limited browser support (Chrome 60 or lower, FireFox 57), as per:

rt span { bottom: 8px; }

thank you,

-Daniel