<!DOCTYPE html>
<html>
  <link rel='stylesheet' type='text/css' href='style.css'>
  <body>
    <fieldset class="ref">
      <legend>
        <fieldset class="ref">
          <legend>
            <button class="ref"></button>
          </legend>
        </fieldset>
      </legend>
    </fieldset>
  </body>
</html>