Errors:
When the attribute “xml:lang” in no namespace is specified, the element must also have the attribute “lang” present with the same value.
A “meta” element with an “http-equiv” attribute whose value is “X-UA-Compatible” must have a “content” attribute with the value “IE=edge”.
Duplicate ID “dropdown01”.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
Attribute “returntext” not allowed on element “ul” at this point.
Attribute “closetext” not allowed on element “ul” at this point.
No “p” element in scope but a “p” end tag seen.
Duplicate ID “dropdownMenuLink”.
The “aria-labelledby” attribute must point to an element in the same document.
Warnings:
Potentially bad value for attribute “content” on element “meta”: Source list contains duplicate source expression "https://www.youtube.com/iframe_api". All but the first instance will be ignored.
The document is not mappable to XML 1.0 due to two consecutive hyphens in a comment.
Consider avoiding viewport values that prevent users from resizing documents.
The “type” attribute is unnecessary for JavaScript resources.
The first occurrence of ID “dropdown01” was here.
The “main” role is unnecessary for element “main”.
The first occurrence of ID “dropdownMenuLink” was here.
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