v151 · css · covered on mdn
Change the "position-anchor" initial value to "normal"
The initial value of the position-anchor property changed from none to normal, aligning Chrome with the specification and with Firefox and Safari. Where the behavior flips: an absolutely positioned element with a non-none position-area and an implicit anchor element now gets that anchor by default (behaving as auto) instead of no default anchor — and the new initial also applies wherever the value comes from CSS-wide initial, a non-inherited unset, a relevant revert outcome, or a reset via the position shorthand. When position-area is none, normal still behaves as none, so nothing changes there.
this feature is documented on MDN
MDN's reference covers the property in full — syntax, all five values (normal, none, auto, <anchor-name>, match-parent), description, formal definition and formal syntax, examples, specifications, and browser compatibility (last modified May 11, 2026). gendn doesn't duplicate that here.
quick reference
| The change | Initial value of position-anchor: none → normal (as none when position-area: none, otherwise as auto) |
|---|---|
| Chrome status | Chrome 151 — Enabled by default (milestone listing); feature detail (ChromeStatus API record, updated 2026-07-13): desktop + Android 151, status text “Proposed” |
| Value availability (BCD) | normal: Chrome 151 · Firefox 151 · Safari 27 · Edge mirror; none: Chrome 144 · Firefox 147 · Safari 27 · Edge mirror; auto: Chrome 125 (partial, per BCD's note) · Firefox 147 · Safari 26 · Edge mirror. Value availability is not the same as initial-value behavior — the initial's own evolution: Chrome implicit (125) → auto (127) → none (144) → normal (151); Firefox auto (147) → normal (151); Safari auto (26) → normal (27) |
| Spec | CSS Anchor Positioning — position-anchor · normal value |
| MDN | position-anchor |
| ChromeStatus | 5351959625334784 — Change the "position-anchor" initial value to "normal" |
| Interactive demo | Chrome Platform Showcase — position-anchor initial value |