See https://drafts.csswg.org/css-pseudo-4/#details-content-pseudo We should make sure those rules are showing in the Rules view, and that any animation on them are showing up in the animation panel.
Bug 1935067 Comment 0 Edit History
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See https://drafts.csswg.org/css-pseudo-4/#details-content-pseudo We should make sure those rules are showing in the Rules view