JSFiddle - React, Tailwind, and code Playground

HTML

<div class="header"></div>

CSS

.header {
    width: 100%;
    height: 128px;
    background: url(http://savepic.su/3951899.png) repeat-x;
    position: relative;
}

.header:after {
      position: absolute;
      width: 98%;
      height: 5%;
      left: 1%;
      z-index: -1;
      bottom: 7px;
      content: "";
      box-shadow: 0 3px 15px #000;
}