CSS Anchor Positioning
CSS Anchor Positioning places one box relative to another named anchor element.
Another example
A table's help popover is anchored to its info button and first tries to open below it. When only 12px is left at the viewport edge, `position-try` moves it above. Anchor positioning places the box. It does not control focus or closing. Build those behaviors separately.
Main parts
- 01Anchor element
- 02Positioned box
- 03Fallback position options
Use it when
Use it for tooltips, popovers, menus, and notes that must follow a trigger and have clear backup positions.
Do not use it when
Anchor positioning does not manage focus or solve every edge collision. Keep a strong fallback for browsers and cases it cannot handle.
Name used in code
anchor-name + position-anchor + position-area/anchor() + position-try Before you ship
Check content order, shared design values, component consistency, contrast, zoom, and layout changes by screen size. Verify every theme, language, and state. If there is motion, offer an equal reduced-motion experience.
Outcome: Use or define CSS Anchor Positioning to make the visual experience clear and easy to use. User context: A table's help popover is anchored to its info button and first tries to open below it. When only 12px is left at the viewport edge, `position-try` moves it above. Anchor positioning places the box. It does not control focus or closing. Build those behaviors separately. Design concept to apply: CSS Anchor Positioning. Why it fits: Use it for tooltips, popovers, menus, and notes that must follow a trigger and have clear backup positions. Do not use it when: Anchor positioning does not manage focus or solve every edge collision. Keep a strong fallback for browsers and cases it cannot handle. Design requirements: Set the content order, shared design values, and reusable components. Define how the layout changes by screen size and state. Keep useful design choices separate from decoration. Inclusion and resilience: Check contrast, zoom, languages, themes, and reduced motion when needed. Do not use color or effects as the only way to show meaning. Acceptance criteria: The design stays clear on phones and desktops, at zoom, in every theme, and in all supported languages. Interactive states stay clear and consistent. Evidence and limits (evidence boundary): A formal document may still be a draft, release candidate, or final version. Check its status and browser or platform support. Unknowns to confirm: Brand limits, amount of content, supported themes and languages, target devices, and design-system rules.
Check this request
Review the current use of CSS Anchor Positioning. Definition: CSS Anchor Positioning places one box relative to another named anchor element. Release checks: Check content order, shared design values, component consistency, contrast, zoom, and layout changes by screen size. Verify every theme, language, and state. If there is motion, offer an equal reduced-motion experience. Before changing code, report the evidence you found, gaps, severity, and the smallest safe fix.