Please see http://vide-greniers.org
and here's the real source of pageValidator message export for "http://vide-greniers.org/":
Generated by CSE HTML Validator Professional v15.01 (https://www.htmlvalidator.com/)
1. Warning: Possibly misspelled words (7, 5 unique): AddThis (1x), départemen (1x), utility (1x), d'antiquaires (2x), Facebook (2x). NOTE: Validation terminated so not all words were checked. 103 total words checked (0 in comments).
2. Warning in line 2 at character 2: [65] This document's DOCTYPE is not a recognized DOCTYPE and may not be valid. Note that most DOCTYPEs are treated as being case-sensitive. The unrecognized DOCTYPE is: "<!DOCTYPE html PUBLIC "" "">". See the description of flag 65 in the documentation for more information and the list of recognized DOCTYPEs.
3. Error in line 2 at character 2: Found an extra document type declaration (<!DOCTYPE ... >). Every HTML and XHTML document should have one and only one document type declaration.
4. Warning in line 11 at character 19: The X-UA-Compatible meta tag may not have any effect if it is not immediately after the "head" start tag. Consider moving this meta tag immediately after the "head" start tag (this is also before the "title" element).
CSE change it for!doctype html>
<html lang="fr">
<head>
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta charset="utf-8">
<title>Agenda des vide-greniers, brocantes et marchés aux puces</title>
<!DOCTYPE HTML>
<!DOCTYPE html PUBLIC "" ""><HTML lang="fr"><HEAD><META content="IE=11.0000"
http-equiv="X-UA-Compatible">
<SCRIPT src="//s7.addthis.com/static/r07/menu174.js" type="text/javascript"></SCRIPT>
<SCRIPT src="//s7.addthis.com/static/r07/lang34/fr.js" type="text/javascript"></SCRIPT>
<SCRIPT src="//s7.addthis.com/static/r07/plugins/layers099.js" type="text/javascript"></SCRIPT>
<META http-equiv="X-UA-Compatible" content="IE=edge">
<META charset="utf-8">
<SCRIPT src="https://www.gstatic.com/pub-config/ca-p ... 8454082.js" type="text/javascript" async=""></SCRIPT>