#nearest-positioned-ancestor
{
border: black solid medium;
height: 150px;
padding: 25px;
position: relative;
width: 50px;
}
div > div
{
background-color: blue;
height: 50px;
left: 50%;
position: absolute;
top: 0px;
width: 50px;
}
Test passes if the blue square is in the top right corner of the black box.