gecko-dev/layout/reftests/margin-collapsing/block-overflow-2-dyn.html

<!DOCTYPE html>
<html class="reftest-wait">
<head>
<style type="text/css">
.separator {
 height: 20px;
 background-color: blue;
}
#overflow {
 height: 200px;
 margin: 20px 0;
 background-color: lightgreen;
}
#child {
 height: 160px;
 margin: 40px 0;
 background-color: green;
}
</style>
<script type="text/javascript">
function test() {
 document.getElementById('overflow').style.overflow = 'hidden';
 document.documentElement.removeAttribute('class');
}
document.addEventListener('MozReftestInvalidate', test, false);
</script>
</head>
<body>
<div class="separator"></div>
<div id="overflow">
 <div id="child"></div>
</div>
<div class="separator"></div>
</body>
</html>