Code Playground

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <svg class="pl" viewBox="0 0 32 32" width="32px" height="32px">
	<clipPath id="ring-clip">
		
		<polygon points="0 0,32 0,32 32,0 32,0 30,14 16.1,0 16.1" />
	</clipPath>
	<g fill="none" stroke="currentcolor" stroke-width="3" transform="rotate(90,16,16)">
		<g opacity="0.2">
			<circle r="3" cx="6.5" cy="16" stroke-dasharray="14.737 4.712" />
			<circle r="9.5" cx="19" cy="16" clip-path="url(#ring-clip)" />
		</g>
		<g stroke-linecap="round">
			
			<circle class="pl__worm1" r="3" cx="6.5" cy="16" stroke-dasharray="14.137 64.4" />
			<circle class="pl__worm2" r="9.5" cx="19" cy="16" stroke-dasharray="14.137 64.4" stroke-dashoffset="14.137" transform="rotate(180,19,16)" />
		</g>
	</g>
</svg>
</body>
</html>

@charset "UTF-8";
@import url(https://fonts.googleapis.com/css?family=Nunito+Sans:300,400,600,700,800);
*,
:after,
:before {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
}
* {
	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%);
	--trans-dur: 0.3s;
	font-size: clamp(16px,0.95rem + 0.25vw,20px);
}
body {
	background-color: var(--bg);
	color: var(--fg);
	display: flex;
	font: 1em/1.5 sans-serif;
	height: 100vh;
	transition:
		background-color var(--trans-dur),
		color var(--trans-dur);
}
.pl {
	display: block;
	margin: auto;
	width: 12em;
	height: auto;

&__worm1,
	&__worm2 {
		animation: worm1-move 1.5s cubic-bezier(0.37,0,0.63,1) infinite;
	}
	&__worm2 {
		animation-name: worm2-move;
	}
}

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

/* Animation */
@keyframes worm1-move {
	from {
		stroke-dashoffset: -2.355;
	}
	to {
		// move by both worm circumferences (78.54)
		stroke-dashoffset: 76.185;
	}
}
@keyframes worm2-move {
	from {
		stroke-dashoffset: 16.492;
	}
	to {
		stroke-dashoffset: -62.045;
	}
}

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