jquery.ParallaxBg.js

  // hero parallax on mousemove
  var movementStrength = 50;
  var height = movementStrength / _window.height();
  var width = movementStrength / _window.width();
  $(".hero").mousemove(function(e){
    var pageX = e.pageX - (_window.width() / 2);
    var pageY = e.pageY - (_window.height() / 2);
    var newvalueX = width * pageX * -1 - 25;
    var newvalueY = height * pageY * -1 - 50;
    $('.hero-bg').css("background-position", newvalueX+"px     "+newvalueY+"px");
  });