<main>
	<header>Turn off computer</header>
	<div class="btn-block">
		<button id="stand-by" class="icon-btn icon-btn--yellow" type="button" aria-label="Stand By">
			<svg class="icon icon--stand-by" viewBox="0 0 24 24" width="24px" height="24px" aria-hidden="true">
				<g fill="none" stroke="#fff">
					<polyline class="icon__part icon__part--1" points="12,2 12,12" stroke-dasharray="10 10" stroke-width="3" data-anim-end />
					<circle class="icon__part icon__part--2" cx="12" cy="12" r="8" stroke-dasharray="50.265 50.265" stroke-dashoffset="-8.378" stroke-width="2" transform="rotate(-120,12,12)" />
				</g>
			</svg>
		</button>
		<span class="btn-block__u">S</span>tand By
	</div>
	<div class="btn-block">
		<button id="turn-off" class="icon-btn icon-btn--red" type="button" aria-label="Turn Off">
			<svg class="icon icon--turn-off" viewBox="0 0 24 24" width="24px" height="24px" aria-hidden="true">
				<g fill="none" stroke="#fff">
					<polyline class="icon__part icon__part--1" stroke-width="3" points="12,7 12,17" data-anim-end />
					<circle class="icon__part icon__part--2" cx="12" cy="12" r="9" stroke-dasharray="56.549 56.549" stroke-linecap="square" stroke-width="2" transform="rotate(-90,12,12)" />
				</g>
			</svg>
		</button>
		T<span class="btn-block__u">u</span>rn Off
	</div>
	<div class="btn-block">
		<button id="restart" class="icon-btn icon-btn--green" type="button" aria-label="Restart">
			<svg class="icon icon--restart" viewBox="0 0 24 24" width="24px" height="24px" aria-hidden="true">
				<g fill="none" stroke="#fff" stroke-dasharray="6 17" stroke-dashoffset="-5">
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="3" transform="translate(12,12) rotate(0)" data-anim-end />
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="2" transform="translate(12,12) rotate(45)" />
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="3" transform="translate(12,12) rotate(90)" />
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="2" transform="translate(12,12) rotate(135)" />
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="3" transform="translate(12,12) rotate(180)" />
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="2" transform="translate(12,12) rotate(225)" />
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="3" transform="translate(12,12) rotate(270)" />
					<polyline class="icon__part icon__part--1" points="0,0 0,11" stroke-width="2" transform="translate(12,12) rotate(315)" />
				</g>
			</svg>
		</button>
		<span class="btn-block__u">R</span>estart
	</div>
	<footer><footer>
		</main>

* {
	border: 0;
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
:root {
	--trans-dur: 0.3s;
	font-size: calc(16px + (24 - 16) * (100vw - 320px) / (2560 - 320));
}
body,
button {
	font: 1em/1.5 Verdana, sans-serif;
}
body {
	background-color: hsl(223,10%,10%);
	display: flex;
	flex-direction: column;
	height: 100vh;
	transition:
		background-color var(--trans-dur),
		color var(--trans-dur);
}
header,
footer {
	background-color: hsl(227,73%,35%);
	display: flex;
	justify-content: space-between;
	align-items: center;
	width: 100%;
	min-height: 4.4rem;
	position: absolute;
}
header {
	font-family: Arial, sans-serif;
	font-size: 1.75em;
	line-height: 1;
	margin-bottom: 0.2rem;
	padding: 0 1.25rem;
	top: 0;
}
footer {
	bottom: 0;
}
header:after {
	background-image: linear-gradient(90deg,hsl(220,50%,47%),hsl(215,77%,91%),hsl(220,50%,47%));
	content: "";
	display: block;
	position: absolute;
	top: 100%;
	left: 0;
	width: 100%;
	height: 0.2rem;
}
main {
	background-image: radial-gradient(circle at center,hsl(220,84%,78%),hsl(224,67%,61%) 12em);
	color: hsl(0,0%,100%);
	display: flex;
	justify-content: center;
	align-items: center;
	margin: auto;
	position: relative;
	max-width: 31.4em;
	width: 100%;
	min-height: 20em;
}
.btn-block {
	width: 9em;
	text-align: center;
}
.btn-block__u {
	text-decoration: underline;
}
.icon-btn {
	background-color: hsl(0,0%,50%);
	border-radius: 0.5em;
	box-shadow:
		0 0 0 2px hsl(0,0%,100%) inset,
		-0.25em -0.25em 0.25em hsla(0,0%,0%,0.5) inset;
	cursor: pointer;
	display: flex;
	margin: 0 auto 0.25em auto;
	outline: transparent;
	position: relative;
	width: 3.3em;
	height: 3.3em;
	-webkit-appearance: none;
	appearance: none;
	-webkit-tap-highlight-color: transparent;
}
.icon-btn:before {
	background-color: hsla(0,0%,100%,0);
	background-image:
		radial-gradient(100% 100% at 0 0,hsla(0,0%,100%,0.5),hsla(0,0%,100%,0) 40%),
		radial-gradient(100% 100% at 90% 90%,hsla(0,0%,100%,0.15),hsla(0,0%,100%,0) 50%);
	border-radius: 0.25em;
	box-shadow: 0.5em 0.5em 0.5em hsla(0,0%,100%,0.15) inset;
	content: "";
	display: block;
	position: absolute;
	inset: 4px;
	transition: background-color var(--trans-dur);
}
.icon-btn:focus-visible:before,
.icon-btn:hover:before {
	background-color: hsla(0,0%,100%,0.2);
}
.icon-btn:active:before {
	background-color: hsla(0,0%,0%,0.2);
}
.icon-btn--green {
	background-color: hsl(119,51%,39%);
}
.icon-btn--red {
	background-color: hsl(12,76%,53%);
}
.icon-btn--yellow {
	background-color: hsl(37,96%,57%);
}
.icon {
	margin: auto;
	pointer-events: none;
	width: 2.4em;
	height: 2.4em;
}
.icon__part {
	animation-duration: 1s;
}
.icon-btn--animated .icon--stand-by .icon__part--1 { animation-name: standBy1; }
.icon-btn--animated .icon--stand-by .icon__part--2 { animation-name: standBy2; }

.icon-btn--animated .icon--stand-by .icon__part,
.icon-btn--animated .icon--turn-off .icon__part {
	transform-origin: 12px 12px;
}
.icon-btn--animated .icon--turn-off .icon__part {
	animation-timing-function: cubic-bezier(0.645, 0.045, 0.355, 1);
}
.icon-btn--animated .icon--turn-off .icon__part--1 { animation-name: turnOff1; }
.icon-btn--animated .icon--turn-off .icon__part--2 { animation-name: turnOff2; }

.icon-btn--animated .icon--restart .icon__part--1 {
	animation-name: restart1;
	animation-timing-function: cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

/* Animations */
@keyframes standBy1 {
	from {
		animation-timing-function: cubic-bezier(0.645, 0.045, 0.355, 1);
		stroke-dashoffset: 0;
		transform: translate(0,0);
	}
	33.33% {
		animation-timing-function: cubic-bezier(0.645, 0.045, 0.355, 1);
		stroke-dashoffset: -7;
		transform: translate(0,7px);
	}
	66.67% {
		animation-timing-function: cubic-bezier(0.645, 0.03, 0.355, 2);
		stroke-dashoffset: 3;
		transform: translate(0,-6px);
	}
	to {
		stroke-dashoffset: 0;
		transform: translate(0,0);
	}
}
@keyframes standBy2 {
	from {
		animation-timing-function: cubic-bezier(0.645, 0.045, 0.355, 1);
		stroke-dashoffset: -8.378;
		transform: rotate(-120deg);
	}
	33.33% {
		animation-timing-function: cubic-bezier(0.645, 0.045, 0.355, 1);
		stroke-dashoffset: 0;
		transform: rotate(-90deg);
	}
	66.67% {
		animation-timing-function: cubic-bezier(0.645, 0.03, 0.355, 2);
		stroke-dashoffset: -13.96;
		transform: rotate(-140deg);
	}
	to {
		stroke-dashoffset: -8.378;
		transform: rotate(-120deg);
	}
}
@keyframes turnOff1 {
	from {
		transform: rotate(0);
	}
	33.33% {
		transform: rotate(45deg);
	}
	66.67% {
		transform: rotate(-225deg);
	}
	to {
		transform: rotate(-180deg);
	}
}
@keyframes turnOff2 {
	from {
		stroke-dashoffset: 0;
		transform: rotate(-90deg);
	}
	33.33% {
		stroke-dashoffset: 7.069;
		transform: rotate(-45deg);
	}
	66.67% {
		stroke-dashoffset: 49.48;
		transform: rotate(-540deg);
	}
	to {
		stroke-dashoffset: 0;
		transform: rotate(-450deg);
	}
}
@keyframes restart1 {
	from { stroke-dashoffset: -5; }
	to { stroke-dashoffset: -28; }
}

window.addEventListener("DOMContentLoaded",() => {
	const standBy = new IconButton("#stand-by");
	const turnOff = new IconButton("#turn-off");
	const restart = new IconButton("#restart");
});

class IconButton {
	animClass = "icon-btn--animated";

	constructor(el) {
		this.el = document.querySelector(el);

		this.init();
	}
	init() {
		const events = ["focus", "mouseover", "touchstart"];
		events.forEach(ev => {
			this.el?.addEventListener(ev,this.iconAnimPlay.bind(this));
		});

		const animEndEl = this.el?.querySelector("[data-anim-end]");
		animEndEl?.addEventListener("animationend",this.iconAnimStop.bind(this));
	}
	iconAnimPlay() {
		this.el?.classList.add(this.animClass);
	}
	iconAnimStop() {
		this.el?.classList.remove(this.animClass);
	}
}