Report unknown custom properties/media as warning, not error#151
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no-unknown-custom-properties and no-unknown-custom-media assert that a referenced custom property/media query is defined nowhere. Static analysis of the CSS captured from a single crawled page can't see definitions set at runtime via JS, in inline style attributes, on a page that wasn't crawled, or produced at build time by PostCSS, so error severity yields frequent false positives. A missing custom property also degrades gracefully to the initial/inherited value rather than producing invalid CSS. Downgrade both to warning so they stay visible without counting as standards errors.
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What
Downgrade
no-unknown-custom-propertiesandno-unknown-custom-mediafromerrortowarning.Why
Both rules assert a negative — that a referenced custom property / custom media query is defined nowhere. Unlike rules that detect genuinely malformed CSS (
property-no-unknown,color-no-invalid-hex, …), this can't be verified by static analysis of the CSS captured from a single crawled page. Custom properties are legitimately defined in places the linter never sees:element.style.setProperty('--x', …)) — common for theming / dark mode,style="--x: …"attributes,:root/section block on a page that wasn't the one crawled,A missing custom property also degrades gracefully —
var(--undefined)with no fallback becomes invalid-at-computed-value-time and falls back to the initial/inherited value, rather than producing invalid CSS. That is warning-shaped, not error-shaped.Real example that prompted this: https://tillvaxtverket.se references four
--lp-filterable-list__control--*theming hooks it never defines. The page renders fine (the inputs just use default styling), but the finding was reported aserror(fel) and pulled down the standards grade.Notes
configurations/standard.jsonis generated, so the change is intools/update_stylelint.py; the regeneratedstandard.jsonis included and is byte-identical to a fresh run against the pinned stylelint 17.12.0.no-unknown-*rules stay aterror.