var bg_im;
var mw = 1280;
var mh = 800;
var ratio = mw/mh;

function updateSizeFirst() 
{
	if (typeof bg_im == "undefined")
		bg_im = document.getElementById("bg-container");
	var size = getWinsize();
	
	if (size.h < (size.w / ratio))
	{
		bg_im.style.width = size.w + "px" ;
		bg_im.style.height = (size.w * 0.625) + "px";	
	}
	else
	{
		bg_im.style.height = size.h + "px" ;
		bg_im.style.width = (size.h * 1.6) + "px";			
	}
	document.getElementById("bg-container").style.display = 'block';
}

function updateSize()
{
	if (typeof bg_im == "undefined")
		bg_im = document.getElementById("bg-container");
	var size = getWinsize();
	
	if (size.h < (size.w / ratio))
	{
		bg_im.style.width = size.w + "px" ;
		bg_im.style.height = (size.w * 0.625) + "px";	
	}
	
}

function getWinsize()
{
	var _obj = new Object();
	if( typeof( window.innerWidth ) == "number" ) 
	{
	//Non-IE
		_obj.w = window.innerWidth;
		_obj.h = window.innerHeight;
	}         
	else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) 
	{
    //IE 6+ in 'standards compliant mode'
		_obj.w = document.documentElement.clientWidth;
		_obj.h = document.documentElement.clientHeight;        
	} 
	else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) 
	{
    //IE 4 compatible
        _obj.w = document.body.clientWidth;
        _obj.h = document.body.clientHeight;
	}
	return _obj;
}