<!DOCTYPE html>
<html class="reftest-wait">
<head>
<style type="text/css">
#separator-top {
 height: 20px;
 margin-bottom: 20px;
 background-color: green;
}
fieldset {
 height: 20px;
 margin: 0;
 padding: 0;
 border: none;
 background-color: green;
}
#separator-bottom {
 height: 20px;
 margin-top: 20px;
 background-color: green;
}
</style>
<script type="text/javascript">
function test() {
 document.getElementsByTagName('fieldset')[0].style.margin = '10px 0';
 document.documentElement.removeAttribute('class');
}
document.addEventListener('MozReftestInvalidate', test, false);
</script>
</head>
<body>
<div id="separator-top"></div>
<fieldset></fieldset>
<div id="separator-bottom"></div>
</body>
</html>