css 过渡
记录一下过渡，改变css样式
<style>
div {
height: 200px;
width: 200px;
background-color: red;
margin: 300px auto;
transition: width 2s, background-color 3s;
-webkit-transition: width 2s, background-color 3s;
}
div:hover {
width: 300px;
background-color: green;
}
</style>
<body>
<div></div>
</body>
