Mathcs.org W3C HTML Markup Validation
HTML markup errors and warnings
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Errors:
Obsolete doctype. Expected “<!DOCTYPE html>”.
Internal encoding declaration “iso-8859-1” disagrees with the actual encoding of the document (“utf-8”).
Bad value “text/html; charset=ISO-8859-1” for attribute “content” on element “meta”: “iso-8859-1” is not a preferred encoding name. The preferred label for this encoding is “windows-1252”.
Stray end tag “input”.
Duplicate ID “primary”.
The “font” element is obsolete. Use CSS instead.
The “align” attribute on the “img” element is obsolete. Use CSS instead.
Saw “"” when expecting an attribute name. Probable cause: “=” missing immediately before.
Attribute “"alt” not allowed on element “img” at this point.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
Warnings:
The first occurrence of ID “primary” was here.
The “border” attribute is obsolete. Consider specifying “img { border: 0; }” in CSS instead.
Attribute “"alt” is not serializable as XML 1.0.
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