shadow.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>shadows</title>
    <style>
        .item{
            border: 2px solid black;
            margin: 3px auto;
            height: 100px;
            width: 100px;
            background-color: yellow;
            box-shadow: 11px 3px 6px 1px green;
        }
        #main{
            display: flex;
            border: 1px solid red;
            height: 275px;
            width:100vw;
            
        }
    </style>
</head>
<body>
    <div id="main">
    <div class="item" id="1">box1</div>
    <div class="item" id="2">box2</div>
    <div class="item" id="3">box3</div>
    <div class="item" id="4">box4</div>
    </div>
</body>
</html>