<!DOCTYPE HTML>
<style>
body {
    margin: 0px;
    padding: 0px;
}

div.test {
    display: flex;
    flex-direction: column;
    justify-content: center;
    position: absolute;
    top: 300px;
    bottom: 10px;
}

div.test .child {
    width: 100px;
    height: 100px;
    background-color: green;
}
</style>
<script src="../../../resources/check-layout.js"></script>
<p>crbug.com/577480: Position centred content of flexboxes correctly after a style change.</p> 
<div style="height: 600px; position: relative;">
    <div class="test" id="test">
        <div class="child" id="child" data-offset-y=240></div>
    </div>
</div>
<div id="console"></div>
<script>
var test = document.getElementById('test');
document.body.offsetTop;
test.style.top = '10px';
checkLayout("#child", document.getElementById("console"));
</script>