onload = function(){
	bannerSet();
	imgPreload();
}

function bannerSet(){
	boxH = document.getElementById('box').offsetHeight;
	sideH = document.getElementById('side-box').offsetHeight;
	bannerH = document.getElementById('minus6').offsetHeight;
	
	marginSet = boxH - (sideH + bannerH) - 8;
	
	if(marginSet <= 0){
		document.getElementById('minus6').style.marginTop = marginSet + 8 + 'px';
	}else{
		document.getElementById('minus6').style.marginTop = marginSet + 'px';
	}
}

function imgPreload(){
	imgObj = new Array();
	
	imgObj[1] = new Image();
	imgObj[1].src = "img/btn1_on.jpg";
	
	imgObj[2] = new Image();
	imgObj[2].src = "img/btn2_on.jpg";
	
	imgObj[3] = new Image();
	imgObj[3].src = "img/btn3_on.jpg";
	
	imgObj[4] = new Image();
	imgObj[4].src = "img/btn4_on.gif";
	
	imgObjN = new Array();
	
	imgObjN[1] = new Image();
	imgObjN[1].scr = "img/btn1.jpg";
	
	imgObjN[2] = new Image();
	imgObjN[2].scr = "img/btn2.jpg";
	
	imgObjN[3] = new Image();
	imgObjN[3].scr = "img/btn3.jpg";

	imgObjN[4] = new Image();
	imgObjN[4].scr = "img/btn4.gif";
}

function btnOver(btnName){
	var overName = btnName.substring(0,4);
	var overNum = btnName.substr(3,1);
	document.getElementById(btnName).src = imgObj[overNum].src;
}

function btnOut(btnName){
	var overNum = btnName.substr(3,1);
	document.getElementById(btnName).src = imgObjN[overNum].scr;
}