为何不能换皮肤
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<link id="css1" rel="stylesheet" type="text/css" href="css1.css"/>
<script id="css2" type="text/javascript">
function Btn(){
var a =document.getElementById("css1")
a.href="css1.css"
}
function Btn2(){
var b =document.getElementById("css2")
a.href="css2.css"
}
</script>
</head>
<body>
<input type="button" name="" id="" value="红色" onclick="Btn()"/>
<input type="button" name="" id="" value="蓝色" onclick="Btn2()"/>
</body>
</html>