XML Schema Validator

Location:	https://denterum.ru/karies-zubov-i-immunitet
Redirect:
Well-formed:	False
Valid:	False
HTTP status code:	200 OK
HTTP Content Type:	text/html; charset=UTF-8
HTTP encoding:	utf-8
XML encoding:	utf-8
Used encoding:	utf-8
Public Identifier:
System Identifier:
Validated as:

No schema was found.
Your document lacks a namespace declaration such as '<html xmlns="http://www.w3.org/1999/xhtml">' on the document element.
Only well-formedness constraints will be checked, while validity constraints will be ignored.

'defer' is an unexpected token. The expected token is '='. (29:62)

  <script src="https://apis.google.com/js/platform.js" async defer>
                                                             ^

If you think the validation result is incorrect or if you have difficulties to understand the messages, feel free to write me an e-mail.