I've tried recently to validate a web page and every time I run the validator it outputs the same errors, although the structure of the page seems legit.
<meta name="viewport" content="width=device-width, initial-scale=1">
Based on looking at the actual errors the document contains, a few recommendations:
https://validator.w3.org/ is written in Perl and uses SGML and DTDs to perform validation and so is very limited in the kinds of checks it can do (e.g., it can’t do precise datatype/microsyntax checking of attribute values. And if your document uses a modern doctype (
<!DOCTYPE html>, the “HTML5” doctype declaration), it just hands the doc of to https://validator.w3.org/nu/ for checking anyway.
Checking https://validator.w3.org/nu/?doc=http://demo.amiron.eu/equilibrium/ brings up two points:
The document at http://demo.amiron.eu/equilibrium/ currently doesn’t have any document type declaration at all. That’s an outright error, because the lack of a doctype can cause unexpected behavior in browsers. And if you use any doctype other than
<!DOCTYPE HTML> it is also easier to get part of the doctype wrong in a way that cause unexpected behavior in browsers.
<meta charset="utf-8">in your documents
The character encoding for http://demo.amiron.eu/equilibrium/ is not declared in the HTTP headers that the document is served with nor in the document itself. Documents on the Web should be encoded in UTF-8 and to be certain their encoding is always made clear to browsers and other tools, documents should always include a
<meta charset="utf-8"> element.