<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<style>
* {
margin:0px;
}
#kaitou {height:100px;
box-shadow:0 10px 1px gray;
}
</style>
</head>
<body>
<div id="kaitou"></div>
<span style="left:20%;top:50%" >欢迎</span>
<span style="left:20%;top:20%">欢迎</span>
</body>
</html>
我设置的top属性都已经百分之50了,但是欢迎这两个字还是在阴影横线上,咋整,大佬们