<!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>