Osa.org W3C HTML Markup Validation
HTML markup errors and warnings
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Errors:
Duplicate attribute “class”.
Element “ul” not allowed as child of element “ul” in this context. (Suppressing further errors from this subtree.)
Bad value “http://www.osa-opn.org/opn/media/Images/Articles/2017/1712/Features/Kentico-Cover-Dec17.jpg?ext=.jpg>” for attribute “src” on element “img”: Illegal character in query: “>” is not allowed.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
Attribute “content” not allowed on element “span” at this point.
The “itemprop” attribute was specified, but the element is not a property of any item.
Warnings:
The “navigation” role is unnecessary for element “nav”.
Article lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all articles.
Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.
This document appears to be written in English. Consider adding “lang="en"” (or variant) to the “html” start tag.
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