# GoogleChromeLabs/container-query-polyfill

A polyfill for CSS Container Queries

Repository: https://github.com/GoogleChromeLabs/container-query-polyfill
Canonical: https://ross.abutalabs.com/products/container-query-polyfill
Homepage: https://npm.im/container-query-polyfill
Language: TypeScript
License: Apache-2.0
License Family: permissive
Last push: 2026-06-22T10:21:09+00:00

## Health v2 (maintenance only)
Score: 62/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 88, release rhythm 8, longevity 100
- inputs: {"age_days": 1755, "days_push": 72, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1148, forks 48 (observed 2026-08-28T04:03:46.045315+00:00)

## What it is
A small (9 kB) polyfill for CSS Container Queries built on ResizeObserver and MutationObserver, supporting the full @container query syntax and container-relative length units. Developed by GoogleChromeLabs, it is now in maintenance mode with no planned feature additions.

## Use cases
- support container queries in older browsers
- polyfill @container rules for Safari 13
- use cqw cqh units where unsupported
- make responsive components work in legacy browsers
- test container query layouts before native support
- add container queries to a site without dropping old browser support

## When to choose
- you need container queries in browsers without native support (pre-2023 Safari, older Chrome/Firefox)
- your styles are in <style> or same-origin <link> elements
- you want a small, official Chrome-team polyfill with full @container syntax support

## When to avoid
- your target browsers natively support container queries
- you rely on inline styles, CSSOM manipulation, Shadow DOM, or CSSContainerRule APIs
- you need active development, new features, or complex sibling selector support

## Facets
- artifact type: library
- maturity: maintenance
- function: ui-components, css-framework, developer-tools
- domain: web-development, frontend, web-design
- platform: browser
- tags: css, polyfill, container-queries, responsive-design, typescript, web-server

## Member repositories
- GoogleChromeLabs/container-query-polyfill (main) score 62

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:46.045315+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:33:47.658547+00:00, confidence not recorded.
  - readme: https://github.com/GoogleChromeLabs/container-query-polyfill (fetched 2026-08-28T04:03:46.045315+00:00, sha 750a0365c069)
  - registry_npm: https://registry.npmjs.org/container-query-polyfill (fetched 2026-08-29T12:39:08.512830+00:00, sha 91cbc7695db5)
- Data as of 2026-08-30T08:39:29.467469+00:00.