body {
	margin:0;
	padding:0;
	background:url(./img/bg.jpg);
}
.intro {
	position:relative;
	width:1400px;
	height:810px;
	margin:0 auto;
	background:url(./img/intro.jpg) no-repeat;
}
.btn-first1, .btn-central1,
.btn-first2, .btn-central2 {
	position:absolute;
	width:270px;
	height:46px;
	cursor:pointer;
	top:308px;
}
.btn-central1 {
	left:200px;
}
.btn-central2 {
	left:341px;
}
.btn-first1 {
	right:215px;
}
.btn-first2 {
	right:145px;
}