Preloader.css

<div class="loader">
  <div class="loader-inner"></div>
</div>

.loader {
  background: none repeat scroll 0 0 #ffffff;
  bottom: 0;
  height: 100%;
  left: 0;
  position: fixed;
  right: 0;
  top: 0;
  width: 100%;
  z-index: 9999;
}
.loader-inner {
  background-image: url("../img/loader.gif");
  background-repeat: no-repeat;
  background-position: center center;
  background-color: #fff;
  height: 60px;
  width: 60px;
  margin-top: -30px;
  margin-left: -30px;
  left: 50%;
  top: 50%;
  position: absolute;
}

$(window).on('load', function() { 
	$('.loader-inner').fadeOut(); 
	$('.loader').delay(400).fadeOut('slow'); 
});