自定义动画对背景色的改变是没有效果的吗？
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
div{width: 100px;height: 100px;background-color:blue; position: absolute; margin: 0px ;}
</style>
<script type="text/javascript" src="jquery-3.3.1.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$('.but').click(function(){
//document.write("1111");
$('.but').animate({
left:'500px',
top:'500px',
width:'toggle',
background:'pink',
opacity:'0.5'
},2000)
})
})
</script>
</head>
<body>
<!-- <button>开始</button> -->
<div></div>
</body>
</html>