False-positive with the CSS :not pseudo-class #1354

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xml:lang="en">
  <head>
    <title>CSS test for :not</title>
    <style>
      @namespace epub "http://www.idpf.org/2007/ops";

      :not(nav.class) > h1 {
        color: blue;
      }

      :not(nav[epub|type="landmarks"]) > h1 {
        text-decoration: underline;
      }
    </style>
  </head>
  <body>
    <nav epub:type="toc">
      <h1>Table of Contents</h1>
    </nav>
    <nav epub:type="landmarks">
      <h1>Guide</h1>
    </nav>
  </body>
</html>