 <p>Now that the parent knows when to switch to the child, it needs to know when
    to switch back. In the case of HTML/CSS, the switch back occurs when the
    lexer encounters an ending &ldquo;style&rdquo; tag, though the lexer should still style
    the tag as an HTML tag:</p>

    <pre><code>
    local css_end_rule = #P('&lt;/style&gt;') * tag
    </code></pre>

    <p>Once the parent loads the child lexer and defines the child&rsquo;s start and end
    rules, it embeds the child with the <a href="#lex