(function() {
  var mX, mY, distance,
    $distance = $('#element h1'),
    $element  = $('#element');

  function calculateDistance(elem, mouseX, mouseY) {
    return Math.floor(Math.sqrt(Math.pow(mouseX - (elem.offset().left+(elem.width()/2)), 2) + Math.pow(mouseY - (elem.offset().top+(elem.height()/2)), 2)));
  }

  $(document).mousemove(function(e) {  
    mX = e.pageX;
    mY = e.pageY;
    distance = calculateDistance($element, mX, mY);
    $distance.text(distance);

    if ( distance > 150) {
      $("div").removeClass("far");
    } else if (distance < 50) {
      $("div").addClass("close"); 
    } else {
      $("div").addClass("far");
      $("div").removeClass("close"); 
    }
  });
})();