<!--
     Any copyright is dedicated to the Public Domain.
     http://creativecommons.org/publicdomain/zero/1.0/
-->
<!DOCTYPE html>
<html>
<head>
<style>

div {
	    height: 10px;
}

#b {
	background: rgba(0,255,0,.5);
}
#c {
    background: -moz-element(#b);
    background-blend-mode: difference;
}

</style>
</head>
<body>
<div id="b"></div>
<div id="c"></div>
</body>
</html>