As per [this comment](https://phabricator.services.mozilla.com/D280081#inline-1530724), viewport units should also be a reason for not caching a highlight pseudo style.
Bug 2013226 Comment 0 Edit History
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As per [this comment](https://phabricator.services.mozilla.com/D280081#inline-1530724), caching needs to properly handle container queries and viewport units.