Overview: If the anchor for an anchored box is partially scrolled out of view in the same axis as the attachment, the anchored box visually detaches from it because it is attached to the theoretical edge of the box rather than the visible edge of the box. This looks weird. You can see the effect in this testcase (though the testcase isn't testing for it): http://wpt.live/css/css-anchor-position/anchor-scroll-position-try-001.html Missing Tests: * Need a test for this behavior. Specification Notes: * The spec should clarify what's expected to happen here, which afaict is that `overflow` should effectively clamp the anchor rectangle.