<!DOCTYPE html>
<html>
<head>
<style>
    svg {
        width: 100px;
        height: 100px;
    }
</style>
</head>
<body>
    <svg>
        <pattern id="r1" width="100%" height="100%" xlink:href="#r2" patternUnits="userSpaceOnUse"/>
        <rect width="100%" height="100%" fill="url(#r1)"/>
    </svg>
    <svg>
        <pattern id="r2">
            <rect width="100%" height="100%" fill="green"/>
        </pattern>
    </svg>
</body>
</html>