title: Creating a "sunken" effect
body: <p>The attached figure has an effect that makes the box look like it has a thickness of about a page and it's sitting on the surface.  All four sides look like they're raised.  I'm looking for the opposite effect that would make the box look like it's "sunken" by about a page thickness. </p>
  
  <p>Thanks for any ideas.<img src="https://i.stack.imgur.com/ZsvJY.png" alt="enter image description here"></p>