Edit in JSFiddle

<div class="frame">
  <div class="mat">
  </div>
</div>

.frame {
  position: relative;
  width: 100%;
  padding-bottom: 82.5%;
  background: black;
  box-shadow: 0 10px 7px -5px rgba(0, 0, 0, 0.3);
}

.mat {
  position: absolute;
  background: white;
  top: 3.0303%; bottom: 3.0303%; left: 2.5%; right: 2.5%;
  box-shadow: 0px 0px 20px 0px rgba(0,0,0,0.5) inset;
}