提示声明那里有问题？？？不知道错哪
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>盒子模型练习题</title>
<style type="text/css">
.myBox{
width:200px;
height:100px;
border:1px solid red;
margin-top:10px;
padding-left:15px
}
</style>
</head>
<body>
<div class="myBox">hello world</div>
<!--在此添加一个div标签，并设置其class属性为myBox-->
</body>
</html>
