Errors:
Attribute “xmlns:og” not allowed here.
Attribute “xmlns:article” not allowed here.
Attribute “xmlns:book” not allowed here.
Attribute “xmlns:profile” not allowed here.
Attribute “xmlns:video” not allowed here.
Attribute “xmlns:product” not allowed here.
When the attribute “xml:lang” in no namespace is specified, the element must also have the attribute “lang” present with the same value.
The “version” attribute on the “html” element is obsolete. You can safely omit it.
The “profile” attribute on the “head” element is obsolete. To declare which “meta” terms are used in the document, instead register the names as meta extensions. To trigger specific UA behaviors, use a “link” element instead.
A “meta” element with an “http-equiv” attribute whose value is “X-UA-Compatible” must have a “content” attribute with the value “IE=edge”.
Text not allowed in element “iframe” in this context.
Bad value “header” for attribute “role” on element “header”.
End tag “a” violates nesting rules.
The “big” element is obsolete.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.
Bad value “footer” for attribute “role” on element “footer”.
Warnings:
Attribute with the local name “xmlns:og” is not serializable as XML 1.0.
Attribute with the local name “xmlns:article” is not serializable as XML 1.0.
Attribute with the local name “xmlns:book” is not serializable as XML 1.0.
Attribute with the local name “xmlns:profile” is not serializable as XML 1.0.
Attribute with the local name “xmlns:video” is not serializable as XML 1.0.
Attribute with the local name “xmlns:product” is not serializable as XML 1.0.
The “type” attribute for the “style” element is not needed and should be omitted.
The “navigation” role is unnecessary for element “nav”.
The “form” role is unnecessary for element “form”.
The “type” attribute is unnecessary for JavaScript resources.
This document appears to be written in German. Consider adding “lang="de"” (or variant) to the “html” start tag.
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