Netzstrategen.com W3C HTML Markup Validation
HTML markup errors and warnings
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Errors:
Bad value “https://api.w.org/” for attribute “rel” on element “link”: The string “https://api.w.org/” is not a registered keyword.
Element “div” not allowed as child of element “ul” in this context. (Suppressing further errors from this subtree.)
Bad value “100%” for attribute “width” on element “iframe”: Expected a digit but saw “%” instead.
The “frameborder” attribute on the “iframe” element is obsolete. Use CSS instead.
The “scrolling” attribute on the “iframe” element is obsolete. Use CSS instead.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
Warnings:
The “banner” role is unnecessary for element “header”.
Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.
This document appears to be written in German. Consider adding “lang="de"” (or variant) to the “html” start tag.
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