Sass & jQuery - Page Preloader

common.js

//Обновлено для jQuery V3
$(window).on('load', function() {
	$(".loader_inner").fadeOut();
	$(".loader").delay(400).fadeOut("slow");
});

main.css

.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 .loader_inner {
    background-image: url("../img/preloader.gif");
    background-size: cover;
    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; }

main.sass

.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/preloader.gif")
	background-size: cover
	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

Page Preloader.html

/*Перед body*/
<div class="loader">
		<div class="loader_inner"></div>
	</div>