<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>CSS实现带阴影效果的三角形</title>
<style>.box {
margin-top:30px;
position: relative;
width: 600px;
height: 400px;
background: #fff;
border: 1px solid #ccc;
box-shadow: 2px 2px 2px #ccc;
}
.box:after {
position: absolute;
top: -20px;
left: 300px;
content: '';
border:solid 20px;
border-color: #fff #fff transparent transparent;
transform: rotate(-45deg);
box-shadow: 2px -2px 2px #ccc;
}</style>
</head>
<body>
<div class="box">
</div>
</body>
</html>
