wp-calypso/packages/components/src/site-thumbnail/style.scss

.site-thumbnail {
	background-color: #f5f7f7;
	display: flex;
	align-items: center;
	justify-content: center;
	position: relative;
	overflow: hidden;
	transition: background-color 1s ease-out;
	border: 1px solid rgb(238, 238, 238);
	box-sizing: content-box;
	border-radius: 4px;
}

.site-thumbnail__image {
	align-self: start;
	width: 100%;
}

.site-thumbnail__image-bg {
	animation: fadein 1s ease-out;
	background-position: center;
	background-size: cover;
	background-repeat: no-repeat;
	width: 150%;
	height: 150%;
	will-change: opacity;
}

.site-thumbnail__image-blur-small {
	filter: blur(50px);
}

.site-thumbnail__image-blur-medium {
	filter: blur(150px);
}

.site-thumbnail-visible {
	animation: fadein 1.5s;
}

.site-thumbnail-loader::before {
	content: "";
	animation-duration: 2.4s;
	animation-fill-mode: forwards;
	animation-iteration-count: infinite;
	animation-name: shimmer;
	animation-timing-function: linear;
	background: linear-gradient(to top, transparent 8%, #f0f0f066 18%, transparent 33%);
	background-size: 100% 1200px;
	width: 100%;
	height: 100%;
	position: absolute;
	left: 0;
	top: 0;
	z-index: 1;
	display: inline-table;
}

.site-thumbnail-icon {
	display: flex;
	align-items: center;
	justify-content: center;
	width: 100%;
	height: 100%;
	position: absolute;
}


@-webkit-keyframes shimmer {
	0% {
		background-position: 0 -100%;
	}
	100% {
		background-position: 0 100%;
	}
}

@keyframes shimmer {
	0% {
		background-position: 0 -1200px;
	}
	100% {
		background-position: 0 1200px;
	}
}

@keyframes fadein {
	from {
		opacity: 0;
	}
	to {
		opacity: 1;
	}
}