JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
    <head>
        <title></title>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <link rel='stylesheet' href='layout.css' type='text/css' media='all' />
    </head>
    <body>
        <div id="back-1"></div>
        <div id="back-2"></div>
        <div id="wrapper">
            <div id="main">
                
            </div>
        </div>
    </body>
</html>

CSS

html { 
	background: #CCC no-repeat center center fixed; 
	-webkit-background-size: cover;
	-moz-background-size: cover;
	-o-background-size: cover;
	background-size: cover;
        margin: 0;
        padding: 0;
}

body {
    position: absolute;
    min-height: 100%;
    height: 100%;
    width: 100%;
    margin: 0;
    padding: 0;
}

#back-1 {
    background-color: red;
    height: 50%;
}

#back-2 {
    background-color: green;
    height: 50%;
}

#wrapper {
    position: inherit;
    top: 1em;
    z-index: 100;
}

#main {
    background-color: #e1e1e8;
    width: 500px;
    height: 350px;
    border: 2px solid #000;
    margin: 0 auto 0;
}