<!DOCTYPE html>
<html class="reftest-wait">
<head>
<style type="text/css">
.separator {
height: 20px;
background-color: green;
}
fieldset {
margin: 0;
padding: 0;
border: none;
background-color: lightgreen;
}
#child {
height: 40px;
background-color: green;
}
</style>
<script type="text/javascript">
function test() {
document.getElementById('child').style.margin = '20px 0';
document.documentElement.removeAttribute('class');
}
document.addEventListener('MozReftestInvalidate', test, false);
</script>
</head>
<body>
<div class="separator"></div>
<fieldset>
<div id="child"></div>
</fieldset>
<div class="separator"></div>
</body>
</html>