请问为什么我使用sweetalert2，显示的是这个样子，请问如何修改
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="./sweetalert2.all.min.js"></script>
</head>
<body>
<button>点击</button>
<script>
var btn = document.querySelector('button');
btn.addEventListener('click', function () {
Swal.fire(
'Good job!',
'You clicked the button!',
'success'
)
})
</script>
</body>
</html>
