<!DOCTYPE html>
<html>
<head>
    <style>
        iframe {
            position: absolute;
            width: 300px;
            height: 150px;
            border: 20px solid rgba(0, 0, 0, 0.5);
            background-color: rgba(255, 255, 255, 0.8);
        }
    </style>
</head>
<body>
    <iframe style="top: 20px" srcdoc="<style> body { background-color: rgba(0, 0, 128, 0.2); } "></iframe>
    <iframe style="top: 120px; left: 100px"srcdoc="<style> body { background-color: rgba(0, 0, 128, 0.2); } "></iframe>
</body>
</html>