JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<div id="firstLayer">
  <img id="image" class="center" src="http://lorempixel.com/400/200/" >
         <div id="mainContent">
          main page content 
         </div>
  </div>
</body>

CSS

body{
 background:gray;  
}
#firstLayer{
    background: url("http://www.enough.de/fileadmin/docimport/images/background-image.png") no-repeat;

    height:500px;
    width:500px;

}
img#image{
 z-index:-1; 
}

.center{
    width: 400px;
    height: 200px;
    position: absolute;
    left: 50%;
    top: 50%;
    margin-left: -200px;
    margin-top: -100px;
}