Does CSS_COLOR_SCHEME_DECLARED affect my score?

Yes. It is an importance 3 rule at RESEARCH confidence, so a failure costs 3 × 0.7 points of impact in the CSS category before that category is normalised to 100.

What does RESEARCH confidence mean?

Backed by large-sample study or industry research, not a specification. Confidence is a declared tier rather than a per-rule number, so every rule backed by the same class of evidence carries the same weight - which is what makes the score reproducible instead of hand-tuned.

How do I check CSS_COLOR_SCHEME_DECLARED on my own site?

Paste your URL into the box above and it runs only this rule, usually in a couple of seconds. It is also included in the CSS checker and in a full scan.

CSSMedium Affects your score

Document declares its supported colour schemes

CSS_COLOR_SCHEME_DECLARED

Without color-scheme the browser paints form controls, scrollbars and the canvas background in the light-mode default, so a dark page gets white scrollbars and unreadable native widgets.

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How this rule is weighted

Importance: 3 / 10; How much this matters relative to other rules.
Confidence: RESEARCH; Backed by large-sample study or industry research, not a specification.
Severity: warning; How the finding is presented when it fails.
Scoring: Counts; A failure costs points in its category.

Impact is importance multiplied by the confidence tier’s weight — SPECIFICATION 1.0, RESEARCH 0.7, EMERGING 0.3, EXPERIMENTAL 0.1. Two rules backed by the same class of evidence therefore always carry the same weight, which is what makes the score reproducible rather than hand-tuned.

Questions about this rule

Does CSS_COLOR_SCHEME_DECLARED affect my score?: Yes. It is an importance 3 rule at RESEARCH confidence, so a failure costs 3 × 0.7 points of impact in the CSS category before that category is normalised to 100.
What does RESEARCH confidence mean?: Backed by large-sample study or industry research, not a specification. Confidence is a declared tier rather than a per-rule number, so every rule backed by the same class of evidence carries the same weight - which is what makes the score reproducible instead of hand-tuned.
How do I check CSS_COLOR_SCHEME_DECLARED on my own site?: Paste your URL into the box above and it runs only this rule, usually in a couple of seconds. It is also included in the CSS checker and in a full scan.

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