Estructura HTML Revelar Area

<div class="reveal-area" id="revealArea">
  <div class="corner-indicators"></div>
  <div class="corner-top-right"></div>
  <div class="corner-bottom-left"></div>
  <div class="focus-brackets">
    <div class="focus-bracket-tr"></div>
    <div class="focus-bracket-bl"></div>
    <div class="focus-cross"></div>
  </div>
</div>