abstract：<html><head><title>我的CSS练习</title> <style> .box { width:100px; height:100px; border:10px dotted #ccc; } .main {
<html>
<head>
<title>我的CSS练习</title>
<style>
.box {
width:100px;
height:100px;
border:10px dotted #ccc;
}
.main {
margin-top:10px;
width:100px;
height:100px;
border-top:10px solid #999;
border-bottom:10px solid #ddd;
border-left:10px solid #333;
border-right:10px solid #777;
border-radius:20px;
}
button {
margin:10px;
border:none;
}
.shadow {
width:300px;
height:40px;
border:1px solid #eee;
box-shadow:0px 5px 20px inset;
background:#009688;
}
</style>
</head>
<body>
<div class="box">1</div>
<div class="main">2</div>
<button>login</button>
<div class="shadow">3</div>
</body>
</html>