<!DOCTYPE html>
<html>
<head>
<title>CSS transition-duration</title>
<style>
div {
width: 100px;
height: 100px;
background: #4535aa;
transition-property: width height;
transition-duration: 4s;
}
div:hover {
width: 300px;
height:400px;
transition-property:height;
transition-duration:6s;
}
</style>
</head>
<body>
<div></div>
</body>
</html>
when i submit it it give me the eror
