var movementStrength = 15;
var height = movementStrength / $(window).height();
var witdth = movementStrength / $(window).width();

$("html").mousemove(function(e){
	
		  var pageX = e.pageX - ($(window).width() / 2);
		  var pageY = e.pageY - ($(window).height() / 2);

		  var newvalueX = height * pageX;
		  var newvalueY = height * pageY;
		  newvalueX = -1 * newvalueX;
		  newvalueY = -1 * newvalueY;
		  $('body').css("background-position", newvalueX+"px "+newvalueY+"px"); 
});