<!DOCTYPE html>
<html>
<head>
<style>
.overlay {
position: absolute;
top: 75px;
left: 75px;
height: 250px;
width: 250px;
border-radius: 50%;
background-color: green;
}
</style>
</head>
<body>
<div class="overlay"></div>
</body>
</html>