title: Is header in legend valid? <legend><h1>Caption</h1></legend>
body: <p>I use this in visual studio but the compiler claimed that <code>h1</code> cannot be nested in <code>legend</code> element, but browser can render it anyway so i am confused that this is valid or not?</p>
  
  <pre><code>&lt;fieldset&gt;
     &lt;legend&gt;
       &lt;h1&gt;Caption&lt;/h1&gt;
     &lt;/legend&gt;
  &lt;/fieldset&gt;
  </code></pre>