<!DOCTYPE html>
<html>
<body>
<p>Test passes if you see a single 100px by 100px green box below.</p>
<div id="host" style="width: 100px; height: 100px;"></div>
<svg>
    <defs>
        <rect id="rect" width="100" height="100" fill="red">
    </defs>
</svg>
<template>
    <svg viewbox="0 0 100 100">
        <defs>
            <rect id="rect" width="100" height="100" fill="green">
        </defs>
        <use href="#rect">
            <rect id="rect" width="50" height="50" fill="red">
        </use>
    </svg>
</template>
<script>

const shadowRoot = host.attachShadow({mode: 'closed'});
shadowRoot.appendChild(document.querySelector('template').content.cloneNode(true)); 

</script>
</body>
</html>