Errors:
Bad value “”content-language”” for attribute “http-equiv” on element “meta”.
Bad value “https://api.w.org/” for attribute “rel” on element “link”: The string “https://api.w.org/” is not a registered keyword.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
End tag “br”.
Duplicate ID “slide-26-layer-1”.
Duplicate ID “slide-26-layer-2”.
Element “div” not allowed as child of element “span” in this context. (Suppressing further errors from this subtree.)
Stray end tag “span”.
End tag “div” seen, but there were open elements.
Unclosed element “span”.
The “frameborder” attribute on the “iframe” element is obsolete. Use CSS instead.
The “scrolling” attribute on the “iframe” element is obsolete. Use CSS instead.
Element “style” not allowed as child of element “footer” in this context. (Suppressing further errors from this subtree.)
Bad value “tel:1900 7141” for attribute “href” on element “a”: Illegal character in scheme data: space is not allowed.
Warnings:
The first occurrence of ID “slide-26-layer-1” was here.
The first occurrence of ID “slide-26-layer-2” was here.
Consider using the “h1” element as a top-level heading only (all “h1” elements are treated as top-level headings by many screen readers and other tools).
Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.
The “language” attribute on the “script” element is obsolete. You can safely omit it.
This document appears to be written in Vietnamese but the “html” start tag has “lang="en-US"”. Consider using “lang="vi"” (or variant) instead.
Viet Nam VN