<div class="preloader">
	<div class="box">
		<div class="box__inner">
			<div class="box__back-flap"></div>
			<div class="box__right-flap"></div>
			<div class="box__front-flap"></div>
			<div class="box__left-flap"></div>
			<div class="box__front"></div>
		</div>
	</div>
	<div class="box">
		<div class="box__inner">
			<div class="box__back-flap"></div>
			<div class="box__right-flap"></div>
			<div class="box__front-flap"></div>
			<div class="box__left-flap"></div>
			<div class="box__front"></div>
		</div>
	</div>
	<div class="line">
		<div class="line__inner"></div>
	</div>
	<div class="line">
		<div class="line__inner"></div>
	</div>
	<div class="line">
		<div class="line__inner"></div>
	</div>
	<div class="line">
		<div class="line__inner"></div>
	</div>
	<div class="line">
		<div class="line__inner"></div>
	</div>
	<div class="line">
		<div class="line__inner"></div>
	</div>
	<div class="line">
		<div class="line__inner"></div>
	</div>
</div>

* {
	border: 0;
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
:root {
	--dur: 2s;
	--bg: #e3e4e8;
	--fg: #17181c;
	font-size: calc(12px + (24 - 12)*(100vw - 320px)/(2560 - 320));
}
body {
	background: var(--bg);
	color: var(--fg);
	display: flex;
	font: 1em/1.5 sans-serif;
	height: 100vh;
	overflow: hidden;
}
.preloader, .box, .box__inner, .box__inner div  {
	transform-style: preserve-3d;
}
.preloader {
	margin: auto;
	position: relative;
	width: 12em;
	height: 24em;
}
.box, .box__inner, .box__inner div, .line {
	position: absolute;
}
.box, .box__inner div, .line__inner  {
	animation-timing-function: ease-in-out;
	animation-iteration-count: infinite;
}
.box, .line__inner {
	animation-duration: var(--dur);
}
.box__inner div, .line__inner {
	background: var(--fg);
}
/* Boxes */
.box, .box__inner {
	width: 100%;
	height: 50%;
}
.box {
	animation-name: popOut;
	top: 50%;
	perspective: 25em;
	transform-origin: 50% 75%;
	z-index: 1;
}
.box + .box {
	animation-delay: calc(var(--dur)/-2);
}
.box__inner, .box__inner div  {
	animation-delay: inherit;
	animation-duration: inherit;
}
.box__inner {
	transform: rotateX(50deg);
	transform-origin: 50% 25%;
}
.box__inner div {
	box-shadow: 0 0 0 0.2em var(--bg) inset;
}
.box__back-flap, .box__front-flap, .box__front {
	width: 6em;
}
.box__left-flap, .box__right-flap, .box__front {
	height: 6em;
}
.box__back-flap, .box__front-flap {
	left: 3em;
	height: 3em;
}
.box__left-flap, .box__right-flap {
	top: 3em;
	width: 3em;
}
.box__back-flap {
	animation-name: backFlap;
	transform: rotateX(-180deg);
	transform-origin: 50% 100%;
}
.box__right-flap {
	animation-name: rightFlap;
	left: 9em;
	transform: rotateY(-179deg);
	transform-origin: 0 50%;
}
.box__front-flap {
	animation-name: frontFlap;
	top: 9em;
	transform: rotateX(180deg);
	transform-origin: 50% 0;
}
.box__left-flap {
	animation-name: leftFlap;
	transform: rotateY(179deg);
	transform-origin: 100% 50%;
}
.box__front {
	top: 3em;
	left: 3em;
	transform: rotateX(-90deg) translateY(50%) translateZ(3em);
}
/* Lines */
.line, .line__inner {
	border-radius: 0.1em;
}
.line {
	top: 0;
	left: calc(50% - 0.1em);
	width: 0.2em;
	height: 6em;
	overflow: hidden;
	transform-origin: 50% 0.1em;
}
.line:nth-child(n + 5) {
	top: 90%;
	transform: translateY(2em);
}
.line:nth-child(3) {
	left: calc(50% - 1.1em);
}
.line:nth-child(4) {
	left: calc(50% + 0.9em);
}
.line:nth-child(5) {
	transform: rotate(-90deg) translateY(2em);
}
.line:nth-child(6) {
	transform: rotate(-45deg);
}
.line:nth-child(7) {
	transform: translateY(-0.5em);
}
.line:nth-child(8) {
	transform: rotate(45deg);
}
.line:nth-child(9) {
	transform: rotate(90deg) translateY(2em);
}
.line__inner {
	animation-duration: calc(var(--dur)/2);
	width: 100%;
	height: 100%;
}
.line:nth-child(n + 3):nth-child(-n + 4) .line__inner {
	animation-name: falling;
}
.line:nth-child(n + 5):nth-child(-n + 9) .line__inner {
	animation-name: landing;
	transform: translateY(-100%);
}
/* Dark Mode */
@media (prefers-color-scheme: dark) {
	:root {
		--bg: #17181c;
		--fg: #e3e4e8;
	}
}
/* Animations */
@keyframes backFlap {
	from, 33% { transform: rotateX(-180deg); }
	41% { transform: rotateX(10deg); }
	45% { transform: rotateX(-27deg); }
	50%, to { transform: rotateX(-15deg); }
}
@keyframes rightFlap {
	from, 33% { transform: rotateY(-179deg); }
	41% { transform: rotateY(10deg); }
	45% { transform: rotateY(-27deg); }
	50%, to { transform: rotateY(-15deg); }
}
@keyframes frontFlap {
	from, 33% { transform: rotateX(180deg); }
	41% { transform: rotateX(-10deg); }
	45% { transform: rotateX(27deg); }
	50%, to { transform: rotateX(15deg); }
}
@keyframes leftFlap {
	from, 33% { transform: rotateY(179deg); }
	41% { transform: rotateY(-10deg); }
	45% { transform: rotateY(27deg); }
	50%, to { transform: rotateY(15deg); }
}
@keyframes popOut {
	from, 21% { transform: translateZ(1px) translateY(0) scale(0,0); }
	33% { transform: translateZ(1px) translateY(-100%) scale(0.75,1.5); }
	41% { transform: translateZ(1px) translateY(-100%) scale(1,1); }
	42%,50% { transform: translateZ(0) translateY(-100%) scale(1,1); }
	55% { transform: translateZ(0) translateY(-100%) scale(0.75,1.5); }
	60% { transform: translateZ(0) translateY(0) scale(1.5,0.75); }
	67% { transform: translateZ(0) translateY(0) scale(1,1); }
	to { transform: translateZ(0) translateY(0) scale(0,0); }
}
@keyframes falling {
	from, 12% { transform: translateY(0%); }
	28%, to { transform: translateY(100%); }
}
@keyframes landing {
	from, 17% { transform: translateY(-100%); }
	41%, to { transform: translateY(100%); }
}