$(window).scroll(function () {
		if ($(this).scrollTop() > 300) {
			$('.scroll-to-top').fadeIn();
		} else {
			$('.scroll-to-top').fadeOut();
		}
	});
	$('.scroll-to-top').click(function () {
		$('body,html').animate({
			scrollTop: 0
		}, 750);
		return false;
	});

	<div class="scroll-to-top"><i class="fa fa-angle-double-up" aria-hidden="true"></i></div>

	<style>
		.scroll-to-top
	position: fixed
	bottom: 30px
	right: 30px
	cursor: pointer
	display: none
	z-index: 10
	background-color: $accent
	padding: 6px 12px 6px
	border-radius: 50px
	transition: all 0.4s ease
	box-shadow: 0 0 5px rgba(255,255,255,.8)
	&:hover
		padding: 8px 15px 8px
		background-color: darken($accent, 10%)
	.fa
		font-size: 30px
		color: #fff
		line-height: 1
	</style>