 <p>I'm not following how your first line of code relates to the "Example". Could you describe the effect you're trying to achieve in words?</p> <p>Your first line reads:</p> <blockquote> <p>(1) Add the class <code>linksbelow</code> to all the <code>tr</code> elements that contain a <code>table.navitem</code> immediately after a <code>tr</code> that contains a <code>table.navheader</code> within <code>.Nav table</code></p> </blockquote> <p>And the example reads:</p> <blockquote> <p>(2) Add a class to any element that matches <code>.Nav table .navheader</code>. The classname is dependent on the result of (1). If the operation in (1) succeeded (presumably meaning if it matched any elements) then the classname should be <code>linksbelow</code>, otherwise <code>Nolinksbelow</code>.</p> </blockquote>