var height = getHeight();
setHeight(height);

function getHeight(){
	var x = 0;
    	if (self.innerWidth)
        {
                x = self.innerHeight;
        }
        else if (document.documentElement && document.documentElement.clientWidth)
        {
                x = document.documentElement.clientHeight;
        }
        else if (document.body)
        {
                x = document.body.clientHeight;
        }
     return x-50;
}

// automatically resize
$(window).resize(function() {
	var newH = getHeight();
	setHeight(newH);
});
	
// set modifications to height function
function setHeight(val){
	$('#background').css('height', val);
}