a11y/doctype · Doctype
src/app.html should open with <!doctype html>.
Severity: info · Category: a11y
Scored info rather than warning: the accessibility half of this rule’s premise has no source. Quirks mode is documented as a layout difference, and the WCAG criterion that used to justify markup-validity checks is obsolete and removed. The layout claim stands, so the rule stands, at the weight its remaining evidence supports.
What it checks
Whether src/app.html opens with <!doctype html> (comments before it are allowed). Project-scoped: read once from src/app.html.
Why it matters
Without a doctype browsers render in quirks mode, which applies different layout and box-model rules than standards mode, so a page can lay out differently from how its stylesheet was designed to behave.
Mode differences
Source analysis only: the CLI and the live dashboard’s static baseline read src/app.html. The Vite plugin’s build pass analyses prerendered HTML and never reads src/app.html, so it reports nothing for this rule, even though a missing doctype is visible in the output it inspects, and the dashboard’s live layer does not evaluate it either; the static result stands.
How to fix
Add <!doctype html> as the first line of src/app.html:
<!doctype html>Disabling
Record the existing finding in the suppressions file (npx svelte-vitals --update-suppressions), or turn the rule off:
export default {
rules: {
'a11y/doctype': 'off'
}
};