<html>
<head>
    <title>Two identical gray squares should appear below.</title>
    <style>
    div {
        width: 100px;
        height: 100px;
        margin: 8px 0px;
    }

    #crossfade {
        background-image: -webkit-cross-fade(url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg'><rect fill='white' width='100' height='100'></rect></svg>"), url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg'><rect fill='black' width='100' height='100'></rect></svg>"), 50%);
    }

    #reference {
        background-color: #808080;
    }
    </style>
</head>
<body>
    <div id="reference"></div>
    <div id="crossfade"></div>
</body>
</html>