[css-borders-4] border-clip with an element reference

[jsnkuhn]

There is a common styling need for borders to be clipped by an overlapping heading element as in the example below.

Would it be possible to expand the "partial borders" property (border-clip/border-limit) to include an element reference that would clip/limit the border to the size of the referenced element?

Something like:

border-clip: url(#heading);

https://drafts.csswg.org/css-backgrounds-4/#partial-borders

[Loirooriol]

So basically you want to expose the <fieldset>/<legend> magic as CSS?