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w3c-css

reference corpus · status live · domain WEB (Web and frontend platform) · lane A · refresh pinned · tags GLOBAL · WEB · STANDARDS

What an agent uses it for

an agent working on layout/selector internals queries this for the csswg draft's algorithm text (the resolution and cascade algorithms are unmemorisable prose)

Use it
curl -fsSLO https://raw.githubusercontent.com/xerj-org/xerj/corpus-hub/tools/xerj-code/hub/w3c-css.json
xerj corpus add --from ./w3c-css.json
xerj corpus index w3c-css then xerj code w3c-css "your question"

Needs the xerj CLI and a local node running; the copy prompt covers both, checks each step, and shows how to stop only the node you started. No shell: the MCP tool xerj_code_search with corpus: "w3c-css", once the corpus is indexed on the node.

Sources and pins

sourcepinlicencesizereview note
w3c-css d06dc03e286cW3C-Software-And-Document 141.6 MB / 3,242 files LICENSE.md at pin: all documents under W3C Software and Document License (BSD-style with notice). | profiler evidence: PROFILER 2026-10-02T00:49:45Z trees-only: files=3242; backlog hint: W3C document licence (verify redistribution terms at pin); api licence: unknown; evidence: LICENSE.md→UNKNOWN

141.6 MB across 3,242 files. Added 2026-10-02.

People behind this corpus

Upstream authors (1)

Owners of the pinned repositories, credited under each repository's licence. They have not signed up here; their pages are attribution.

w3c@w3c · upstream

All contributors.

Rights

W3C-Software-And-Document. Redistribution permitted with attribution per the licence review. The review block records a human opening each licence file at the pin. Detector output is a hint, never the verdict.

Retrieval spot-check (G7)

4.0/5 relevant. Graded .

Q: What is the difference between repeat(auto-fill) and repeat(auto-fit) in a grid template?
expect:
top-5: w3c-css/css-color-4/math.js / w3c-css/css-grid-2/Overview.bs / w3c-css/css-grid-1/Overview.bs / w3c-css/css-grid-2/Overview.bs / w3c-css/css-grid-3/Overview.bs
grade: pass
Q: Why would I use :where() instead of :is() when both take a selector list?
expect:
top-5: w3c-css/css-color-4/math.js / w3c-css/selectors-4/Selectors_4_Explainer.md / w3c-css/web-animations/respec/respec.js / w3c-css/selectors-4/Selectors_4_Explainer.md / w3c-css/css-cascade-6/Overview.bs
grade: partial
Q: Why does CSS compute color difference in Oklab instead of CIE Lab?
expect:
top-5: w3c-css/css-color-4/Overview.bs / w3c-css/css-color-4/Overview.bs / w3c-css/css-images-4/Overview.bs / w3c-css/css-color-4/Overview.bs / w3c-css/css-color-4/test-coverage.html
grade: pass
Q: How can a stylesheet detect whether the user prefers a dark or light color scheme?
expect:
top-5: w3c-css/mediaqueries-5/Overview.bs / w3c-css/mediaqueries-5/Overview.bs / w3c-css/mediaqueries-5/Overview.bs / w3c-css/mediaqueries-5/Overview.bs / w3c-css/mediaqueries-5/Overview.bs
grade: pass
Q: Why won't flex items shrink below the size of their content even when the container is too small?
expect:
top-5: w3c-css/css-color-4/math.js / w3c-css/css-align-3/Overview.bs / w3c-css/css-overflow-5/middle-truncation.md / w3c-css/css-grid-2/Overview.bs / w3c-css/css-align-3/Overview.bs
grade: partial

Agent score

From structured reviews that AI agents send after they use this corpus: through xerj hub pull, MCP queries, or the xerj_corpus_feedback tool. Each review rates usefulness 1–5, whether the answer was found, and freshness. This is not the human hub star count shown above. The two are never mixed.

Loading agent reviews…

Score = Bayesian mean of usefulness (prior 3.0 with weight 5), so a few reviews cannot swing it. One voice per installation per corpus per week; abnormal-volume reviewers are dropped. Coverage gaps appear only once 3 or more agents report the same one. How it works.

Traffic

Traffic stats load from /api/hub-traffic when this page runs JavaScript.

Views: visits to this page (search-engine crawlers excluded). Unique: distinct visitors per day, by a hash salted with the day, so the 14-day unique figure adds up daily uniques. Pulls: growth of the GitHub release download count of this corpus’s pack (xerj hub pull downloads from there; includes our own pack-verification downloads). Searches: hosted-hub queries for this corpus. Referring sites appear after 3 views. What is collected.

Agent usage

Usage stats load from /api/hub-usage when this page runs JavaScript.

Counted: requests agents send to the hosted hub API (hub.xerj.org/api/v1/code, /def) for this corpus. Queries on your own node (xerj code, xerj ask with a local pack, the MCP tools) never leave your machine and are not counted. Templates replace identifiers, versions, paths, numbers and quoted text with placeholders; one is shown only once it has been seen 3 times in 30 days, and any word asked fewer than 3 times shows as <term>. Raw queries are never published. What is collected.