// JavaScript Document
var rel = 0;
var midX = 0;
var midY = 0;

function get_image() {
	var Img = document.getElementById("MainBg");
	w = parseInt(Img.width);
	h = parseInt(Img.height);
	rel = (w > h) ? (w / h) : (w / h);
	
	set_bg_size();
	document.getElementById("Bg").style.visibility = "visible";
}
function set_bg_size()
{
	doc_w = parseInt(document.documentElement.clientWidth);
	doc_h = parseInt(document.documentElement.clientHeight);

	midX = doc_w / 2;
	midY = doc_h / 2;
	
	var w = doc_w;
	var h = w / rel;
	
	if (h < doc_h) {
		h = doc_h;
		w = h * rel;
	}
	var x = (midX) - (w/2);
	var y = (midY) - (h/2);
	
	var BgImg = document.getElementById("MainBg");
	BgImg.width = w;
	BgImg.height = h;
	BgImg.style.top = y + "px";
	BgImg.style.left = x + "px";
}