Tambahkan drop shadow yang sangat halus (CSS) ke elemen (html)

/*CSS/STYLE.CSS START*/
p {
    padding: 10px;
}

.box {
    padding: 20px;
    width: 50%;
    margin: 30px auto;
    background: #666;
    color: #fff;
}

/* offset-x | offset-y | blur-radius | spread-radius | color */
#box1 {
    box-shadow: 0px 2px 7px 1px grey;
}
/*CSS/STYLE.CSS STOP*/

----------------------------------------------------------------------------

/*HTML START*/
<!doctype html>
<html>

<head>
    <meta charset="utf-8">
    <meta name="description" content="">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Untitled</title>
    <link rel="stylesheet" href="css/style.css">
</head>
<body>
<div id="box1" class="box">Box1</div>
<div id="box2" class="box">Box2</div>
<div id="box3" class="box">Box3</div>
</body>
</html>
/*HTML STOP*/
Zaphod Beeblebrox