HTML Guide for html
Instead of using the isolang attribute to define the language of the document, you can use lang with an ISO 639-1 two character code.
For example, for Portuguese:
<html lang="pt">
A stray start tag <html> has been found in the document. As this tag defines the start of the whole HTML document, it should appear only once.
In HTML5, there’s no need to specify the version attribute - it is now obsolete. Here’s an example minimal HTML document to start with:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Test</title>
</head>
<body>
<p></p>
</body>
</html>