<!DOCTYPE html> <title>Invalid languages</title> <link rel="match" href="lang-xyzzy-ref.html"> <link rel="author" title="Ms2ger" href="mailto:ms2ger@gmail.com"> <link rel="help" href="https://html.spec.whatwg.org/multipage/#the-lang-and-xml:lang-attributes"> <link tel="help" href="http://www.w3.org/TR/CSS2/selector.html#lang"> <meta name="flags" content="css21"> <style>:lang(xyzzy) { color: green; }</style> <body> <div id="test"> <p id="testp" lang="xyzzy">ABC</p> </div>