*{margin: 0;padding: 0;}
			div{width:600px;height: 1000px;background:#ddd;margin:100px auto;padding-top:200px;}
			p{width: 300px;height: 300px;margin: 0 auto;background:#ccc}
			a{position: fixed;top:10px;left:10px;width: 80px;height:80px;background: #0B8AFD;color:#fff;}