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Checks for valid HTML5 doctype declaration
Rule IDcore/doctype
CategoryCore SEO
ScopePer-page
Severitywarning
Weight5/10

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Solution

Add <!DOCTYPE html> at the very start of your HTML document, before the <html> tag. This declaration tells browsers to render the page in standards mode rather than quirks mode, ensuring consistent rendering across browsers. Without a proper doctype, browsers may render the page inconsistently.

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Enable / Disable

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Disable this rule

squirrel.toml
[rules]
disable = ["core/doctype"]

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Disable all Core SEO rules

squirrel.toml
[rules]
disable = ["core/*"]

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Enable only this rule

squirrel.toml
[rules]
enable = ["core/doctype"]
disable = ["*"]