Warnings:
The “navigation” role is unnecessary for element “nav”.
Attribute “xmlns” is not serializable as XML 1.0.
The first occurrence of ID “example-pager” was here.
The first occurrence of ID “presentation” was here.
The first occurrence of ID “video” was here.
This document appears to be written in English. Consider adding “lang="en"” (or variant) to the “html” start tag.
Errors:
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
Attribute “href” not allowed on element “span” at this point.
Bad value “” for attribute “action” on element “form”: Must be non-empty.
Duplicate attribute “class”.
Element “div” not allowed as child of element “button” in this context. (Suppressing further errors from this subtree.)
End tag “button” seen, but there were open elements.
Unclosed element “div”.
No “li” element in scope but a “li” end tag seen.
Element “ul” not allowed as child of element “ul” in this context. (Suppressing further errors from this subtree.)
End tag “nav” seen, but there were open elements.
Unclosed element “ul”.
Bad value “http://www.w3.org/1999/html” for the attribute “xmlns” (only “http://www.w3.org/1999/xhtml” permitted here).
Bad value “100%” for attribute “width” on element “img”: Expected a digit but saw “%” instead.
Duplicate ID “example-pager”.
Duplicate ID “presentation”.
Duplicate ID “video”.
Bad value “140px” for attribute “width” on element “img”: Expected a digit but saw “p” instead.
Bad value “81px” for attribute “height” on element “img”: Expected a digit but saw “p” instead.
Attribute “escape” not allowed on element “a” at this point.
Element “a” not allowed as child of element “ul” in this context. (Suppressing further errors from this subtree.)
Bad value “group” for attribute “rel” on element “a”: The string “group” is not a registered keyword.
Stray end tag “div”.
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