#slider{}	
#slider ul, #slider li{
	margin-top : 20;
	padding: 0;
	list-style:none;
	}
#slider li{ 
	width:310px;
	height:310px;
	overflow:hidden; 
	}	
#prevBtn, #nextBtn{ 
	display:block;
	width:30px;
	height:77px;
	position:absolute;
	left:-30px;
	top:71px;
	}	
#nextBtn{ 
	left:310px;
	}