See https://wpt.fyi/results/mathml/relations/css-styling/default-properties-on-the-math-root.html We need to add UA rules from https://w3c.github.io/mathml-core/#the-top-level-math-element
*** Bug 156839 has been marked as a duplicate of this bug. ***
Pull request: https://github.com/WebKit/WebKit/pull/6351
Committed 256606@main (e79a6f098c81): <https://commits.webkit.org/256606@main> Reviewed commits have been landed. Closing PR #6351 and removing active labels.
<rdar://problem/102276431>