css box-shadow 阴影 - 自学教程(runoops.com)

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"> 
<title>css box-shadow 阴影 - 自学教程(runoops.com)</title> 
<style>
#boxshadow {
	width:300px;
    position: relative;
    -moz-box-shadow: 1px 2px 4px rgba(0, 0, 0,0.5);
    -webkit-box-shadow: 1px 2px 4px rgba(0, 0, 0, .5);
    box-shadow: 1px 2px 4px rgba(0, 0, 0, .5);
    padding: 10px;
    background: white;
}

/* Make the image fit the box */
#boxshadow img {
    border: 1px solid #8a4419;
    border-style: inset;
}

#boxshadow::after {
    content: '';
    position: absolute;
    z-index: -1; /* hide shadow behind image */
    -webkit-box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);
    -moz-box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);
    box-shadow: 0 15px 20px rgba(0, 0, 0, 0.3);
    width: 70%;
    left: 15%; /* one half of the remaining 30% */
    height: 100px;
    bottom: 0;
}
</style>
</head>
<body>

</body>
</html>