https://jsfiddle.net/UnsungHero97/80qod7aL/2/

HTML

<div class="box_shadow"></div>

CSS

.box_shadow {
  background-color: #1C90F3;
  width: 200px;
  height: 100px;
  margin: 50px;
}

.box_shadow:after {
  content: "";
  width: 190px;
  height: 1px;
  margin-top: 98px;
  margin-left: 5px;
  display: block;
  position: absolute;
  z-index: -1;
  -webkit-box-shadow: 0px 0px 8px 2px #444444;
     -moz-box-shadow: 0px 0px 8px 2px #444444;
          box-shadow: 0px 0px 8px 2px #444444;
}