v151 · css · anchor-positioning

Position-Anchor Initial Value: "normal"

The initial value of position-anchor changed from none to normal. When position-area is set, normal resolves to auto, so an anchored element automatically references its implicit anchor without an explicit position-anchor declaration.

concepts

  1. Anchor Default Behavior

    Two identical tooltip setups — one relies on the new normal default, the other declares position-anchor: auto explicitly. Toggle position-area to see both behave identically.

  2. Computed Value Probe

    Read the computed position-anchor from an element live. See that it resolves to normal (not none) as the initial value, and that it becomes auto when position-area is active.

why it shipped

Aligning with the CSS Anchor Positioning spec and other browsers. The none initial was a Chromium deviation that caused interop issues: an element with position-area but no explicit position-anchor would not anchor, while other browsers automatically linked it. The normal value bridges both behaviours correctly.

references

implementation reference

Need the exact API surface, compatibility boundaries, errors, lifecycle, and source links? Read the matching gendn reference ↗