.div_base {
	position:absolute;
	left:50%;
	top:0px;
	width:712px;
	height:747px;
	z-index:1;
	margin-left: -356px;
	background-attachment: scroll;
	background-image: url(images/img_bck_base.png);
	background-repeat: repeat-y;
	background-position: left top;
}