Box shadow on bottom of Div element using negative spread.

<div class="container">
   <div class="row">
       <div class="col-md-6 shadow">
           
       </div>
   </div>
    
</div>  

.shadow {
     height:100px;
     width:400px;
     box-shadow: 0px 3px 3px -3px #444;
}