SOURCE

<main>
	<svg class="ap" viewBox="0 0 128 256" width="128px" height="256px" xmlns="http://www.w3.org/2000/svg">
		<defs>
			<linearGradient id="ap-grad1" x1="0" y1="0" x2="0" y2="1">
				<stop offset="0%" stop-color="hsl(223,90%,55%)" />
				<stop offset="100%" stop-color="hsl(253,90%,55%)" />
			</linearGradient>
			<linearGradient id="ap-grad2" x1="0" y1="0" x2="0" y2="1">
				<stop offset="0%" stop-color="hsl(193,90%,55%)" />
				<stop offset="50%" stop-color="hsl(223,90%,55%)" />
				<stop offset="100%" stop-color="hsl(253,90%,55%)" />
			</linearGradient>
		</defs>
		<circle class="ap__ring" r="56" cx="64" cy="192" fill="none" stroke="#ddd" stroke-width="16" stroke-linecap="round" />
		<circle class="ap__worm1" r="56" cx="64" cy="192" fill="none" stroke="url(#ap-grad1)" stroke-width="16" stroke-linecap="round" stroke-dasharray="87.96 263.89" />
		<path class="ap__worm2" d="M120,192A56,56,0,0,1,8,192C8,161.07,16,8,64,8S120,161.07,120,192Z" fill="none" stroke="url(#ap-grad2)" stroke-width="16" stroke-linecap="round" stroke-dasharray="87.96 494" />
	</svg>
</main>

* {
	border: 0;
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
:root {
	--hue: 223;
	--bg: hsl(var(--hue),10%,90%);
	--fg: hsl(var(--hue),10%,10%);
	font-size: calc(16px + (24 - 16) * (100vw - 320px) / (1280 - 320));
}
body {
	background-color: #1f1f1f;
	color: var(--fg);
	font: 1em/1.5 sans-serif;
	height: 100vh;
	display: grid;
	place-items: center;
	transition: background-color 0.3s;
}
main {
	padding: 1.5em 0;
}

.ap {
	width: 8em;
	height: 16em;
}
.ap__ring {	
	transition: stroke 0.3s;
}
.ap__worm1,
.ap__worm2 {
	animation-duration: 3s;
	animation-iteration-count: infinite;
}
.ap__worm1 {
	animation-name: worm1;
}
.ap__worm2 {
	animation-name: worm2;
	visibility: hidden;
}

/* Dark theme */
@media (prefers-color-scheme: dark) {
	:root {
		--bg: hsl(var(--hue),10%,10%);
		--fg: hsl(var(--hue),10%,90%);
	}
	.ap__ring {
		stroke: hsla(var(--hue),10%,90%,0.1);
	}
}

/* Animtions */
@keyframes worm1 {
	from {
		animation-timing-function: ease-in-out;
		stroke-dashoffset: -87.96;
	}
	20% {
		animation-timing-function: ease-in;
		stroke-dashoffset: 0;
	}
	60% {
		stroke-dashoffset: -791.68;
		visibility: visible;
	}
	60.1%,
	to {
		stroke-dashoffset: -791.68;
		visibility: hidden;
	}
}
@keyframes worm2 {
	from,
	60% {
		stroke-dashoffset: -87.96;
		visibility: hidden;
	}
	60.1% {
		animation-timing-function: cubic-bezier(0,0,0.5,0.75);
		stroke-dashoffset: -87.96;
		visibility: visible;
	}
	77% {
		animation-timing-function: cubic-bezier(0.5,0.25,0.5,0.88);
		stroke-dashoffset: -340;
		visibility: visible;
	}
	to {
		stroke-dashoffset: -669.92;
		visibility: visible;
	}
}