a29.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>

        #a {
            border: 2px solid green;
            width: 200px;
            height: 200px;
            margin: 20px 50px 100px 200px;
                    /* 12noon   3pm    6pm     9pm */
                    /* top  right  bottom  left */
        }

        #b {
            border: 2px solid red;
            width: 200px;
            height: 200px;
        }
    </style>
</head>
<body>
    
    <div id="a"></div>
    <div id="b"></div>

</body>
</html>