* {
	margin:0;
	padding:0;
}
#ballBox {
	position:relative;
	margin:0 auto;
	overflow:hidden;
	background-color:#000;
}
#ballBox div {
	text-align:center;
	font-family:"微软雅黑";
	font-weight:bold;
	color:#fff;
}
#ballBox button {
	outline:none;
	cursor:pointer;
	border:none;
	background-color:#fff;
	height:50px;
	position:absolute;
	padding:0 10px;
	top:20px;
	left:50%;
	font:20px "微软雅黑";
	margin-left:-70px;
	z-index:5;
}
#ballBox button:active {
	background-color:#bbb;
}