<html>
<head>

<style>
#outer {
    padding-top: 200px;
    /* background-size is implicitly set to initial via the background shorthand. */
	background:-webkit-gradient(
	    linear, 
	    left top, 
	    left bottom, 
	    color-stop(0%, rgba(255,255,0,0)), color-stop(100%, rgba(0,0,0,1))
	);
}

#inner {
    height: 300px;
}
</style>

</head>
<body'>
<div id='outer'>
    <div id='inner'>
    </div>
</div>
</body>
</html>