Teachingchannel.org W3C HTML Markup Validation
HTML markup errors and warnings
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Errors:
A “meta” element with an “http-equiv” attribute whose value is “X-UA-Compatible” must have a “content” attribute with the value “IE=edge”.
Bad value “cleartype” for attribute “http-equiv” on element “meta”.
Duplicate attribute “class”.
Bad value “” for attribute “id” on element “li”: An ID must not be the empty string.
Duplicate ID “main-menu”.
Duplicate ID “”.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
The “itemprop” attribute was specified, but the element is not a property of any item.
Warnings:
The “type” attribute is unnecessary for JavaScript resources.
The first occurrence of ID “main-menu” was here.
The first occurrence of ID “” was here.
The “banner” role is unnecessary for element “header”.
The “main” role is unnecessary for element “main”.
The “contentinfo” role is unnecessary for element “footer”.
Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.
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