<!DOCTYPE html><!--h5写法 -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<style type="text/css">
.fa{
background-color:pink;
width:300px;
height:200px;
}
.son{
background-color:blue;
}
</style>
</head>
<body>
<div class="fa">
<div class="son">111</div>
</div>
</body>
</html>