Bounce preloader

bounce.css

.preloader {
	display: inline-block;
	position: relative;
	-webkit-transition: all 0.5s ease;
	transition: all 0.5s ease;
}

.item {
	width: 30px;
	height: 30px;
	border-radius: 50%;
	background: #2ecc71;
	opacity: 0.6;
	position: absolute;
	top: 0;
	left: 0;
	-webkit-animation: bounce 2s infinite ease-in-out;
	animation: bounce 2s infinite ease-in-out;
}

.item:nth-child(2) {
	-webkit-animation-delay: -1s;
	animation-delay: -1s;
}

@-webkit-keyframes bounce {
	0%, 100% {
		-webkit-transform: scale(0);
	}
	50% {
		-webkit-transform: scale(1);
	}
}

@keyframes bounce {
	0%, 100% {
		transform: scale(0);
		-webkit-transform: scale(0);
	}
	50% {
		transform: scale(1);
		-webkit-transform: scale(1);
	}
}

bounce.html

<div class="preloader">
	<div class="item"></div>
	<div class="item"></div>
</div>