Ou.edu.vn W3C HTML Markup Validation
HTML markup errors and warnings
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Errors:
Bad value “https://api.w.org/” for attribute “rel” on element “link”: The string “https://api.w.org/” is not a registered keyword.
Bad value “” for attribute “action” on element “form”: Must be non-empty.
Bad value “attachment wp-att-3092” for attribute “rel” on element “a”: The string “wp-att-3092” is not a registered keyword.
Bad value “attachment wp-att-3093” for attribute “rel” on element “a”: The string “wp-att-3093” is not a registered keyword.
Bad value “attachment wp-att-3094” for attribute “rel” on element “a”: The string “wp-att-3094” is not a registered keyword.
Bad value “attachment wp-att-3091” for attribute “rel” on element “a”: The string “wp-att-3091” is not a registered keyword.
Duplicate ID “slide”.
No “li” element in scope but a “li” end tag seen.
Warnings:
Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.
The first occurrence of ID “slide” was here.
Text run is not in Unicode Normalization Form C.
This document appears to be written in Vietnamese but the “html” start tag has “lang="en-US"”. Consider using “lang="vi"” (or variant) instead.
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