JSFiddle - React, Tailwind, and code Playground

HTML

<body class="library">



 <div id="content">        
        <div id="navBar">
            <p>Hey</p>
        </div>
        
        <div id="contentWindow">
                <p>Hej</p>
        </div>	
    </div>		
</body>

CSS

body.library, html {
	background:black;
	height:100%;
	margin: 0; 
	padding: 0; 
	border: 0 none;
}




div#content{
	display:block;
	position:relative;
	background:#FF0000;	
    min-width:70px;
	margin-right:0px;
    margin-left:50px;
    margin-top:0px;
    margin-bottom:0px;
	height:100%;
}

div#contentWindow{
	display: block;
    position:absolute;
    height:auto;
    bottom:0;
    top:0;
    left:0;
    right:0;
    margin-top:50px;
    margin-bottom:20px;
    margin-right:20px;
    margin-left:20px;
    background-color: green;
}

div#navBar {
	list-style-type:none;
	margin:0;
	padding:0;
	overflow:hidden;
	text-align:center;
}