Ivan Korsakov

$(window).scroll(function () {
     if  ($(window).scrollTop() == $(document).height() - $(window).height()) {
          // Достигли низа страницы
     }
});

.one {
  height: 200px;
  width: 33%;
}

.two {
  height: 200px;
  width: 33%;
}

<div class="bg-outer b1">
	<div class="bg-top"></div>
	<div class="bg-inner">Test</div>
</div>

html {
	min-height: 100%;
	background-color: #fff;
}
.bg-outer {
	overflow: hidden;
	position: relative;
	display: inline-block;
	margin: 50px;
	vertical-align: top;
	font-size: 2em;
	color: #fff;
}
.b1 {
	width: 400px;
}
.b2 {
	width: 250px;
}
.b1 .bg-top {
	box-shadow: 0 0 0 1000px #669;
}
.b2 .bg-top {
	box-shadow: 0 0 0 1000px #c33;
}
.bg-inner {
	position: relative;
	padding: 30px 30px 50px;
}
.bg-top {
	position: absolute;
	top: 100%;
	left: 50%;
	width: 500%;
	border-radius: 50%;
	transform: translate(-50%, -1%);
}
.bg-top:before {
	content: "";
	display: block;
	padding: 100% 0 0;
}