Datahero.com 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 “https://api.w.org/” for attribute “rel” on element “link”: The string “https://api.w.org/” is not a registered keyword.
The element “button” must not appear as a descendant of the “a” element.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
Attribute “gesture” not allowed on element “iframe” at this point.
Attribute “allow” not allowed on element “iframe” at this point.
The “frameborder” attribute on the “iframe” element is obsolete. Use CSS instead.
Bad value “” for attribute “src” on element “img”: Must be non-empty.
No “p” element in scope but a “p” end tag seen.
Warnings:
Consider avoiding viewport values that prevent users from resizing documents.
The “navigation” role is unnecessary for element “nav”.
Empty heading.
This document appears to be written in English. Consider adding “lang="en"” (or variant) to the “html” start tag.
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