This is the answer that took me 2 hours to solve. I wish whoever is responsible of fixing issues would go back to each lesson and fix all errors. Not cool to be stuck and not able to move forward with no help at all. They should at least let you move forward regardless.
<!DOCTYPE html>
<html>
<head>
<title>CSS transition-duration</title>
<style>
div {
width: 100px;
height: 100px;
background: #4535aa;
transition-property: width, height;
transition-duration: 4s, 6s;
}
div:hover {
width: 300px;
height: 400px;
}
</style>
</head>
<body>
<div></div>
</body>
</html>
