<style>
        div {
            width: 200px;
            height: 50px;
            background-color: orange;
            text-align: center;
            line-height: 50px;
            font-size: 18px;
            color: aliceblue;
            margin: auto;
            position: fixed;
            left: 50%;
            top: 50%;
            margin-left: -100px;
            margin-top: -25px;
            transition: transform 5s cubic-bezier(.3,.64,.93,.7) 0s;
        }
        div:hover{
            transform: rotate(360deg) scale(2);
        }
    </style>

​<div>www.imooc.com</div>