Codly

html

<input type="checkbox" id="toggle" name="toggle" value="is_on">
<label for="toggle" class="toy-toggle">
	<div class="border1"></div>
	<div class="border2"></div>
	<div class="border3"></div>
	<div class="handle">
		<div class="handle-off"></div>
		<div class="handle-on"></div>
	</div>
</label>

css

*, *:before, *:after {
	border: 0;
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
body {
	background: linear-gradient(#fff,#ccc);
	display: flex;
	height: 100vh;
	--on: #88e661;
	--off: #f0f0f0;
	--transDur: 0.6s;
}
input {
	position: fixed;
	transform: translateX(-100%);
}
.toy-toggle {
	background:
		radial-gradient(at top left,#fff 10%,#fff0 20%),
		radial-gradient(at top right,#fff 20%,#e4e4e4 35%);
	border-radius: 6em;
	box-shadow:
		0 0 0.25em #0002,
		0 3em 1.5em 0.5em #0002;
	cursor: pointer;
	display: block;
	font-size: 12px;
	position: relative;
	margin: auto;
	width: 20em;
	height: 12em;
	-webkit-tap-highlight-color: transparent;
}
.toy-toggle div {
	position: absolute;
}
.toy-toggle > div {
	top: 50%;
	left: 50%;
}
.toy-toggle > div:not(.handle) {
	transform: translate(-50%,-50%);
}
.border1 {
	background: #f0f0f0;
	border-radius: 5.5em;
	box-shadow: 0 0 0.2em 0.1em #f0f0f0;
	width: 19em;
	height: 11em;
}
.border2 {
	background: linear-gradient(0deg,#fff 33%,#ccc 45%);
	border-radius: 4.75em;
	box-shadow: 0 0 0.2em 0.3em #f0f0f0 inset;
	width: 16.5em;
	height: 9.5em;
}
.border3, .handle {
	background: linear-gradient(90deg, var(--on) 50%, var(--off) 0);
}
.border3 {
	background-position: 75% 0;
	background-size: 200% 100%;
	border-radius: 4.25em;
	box-shadow:
		0 0 0.1em 0.1em #ddd inset,
		0 1.5em 1.5em 1em #0004 inset,
		0 0 0 4.25em #0002 inset;
	width: 15.5em;
	height: 8.5em;
	transition: background-position var(--transDur) ease-in-out;
}
.handle {
	border-radius: 50%;
	box-shadow: 0 0 0.5em 0 #0007;
	width: 8.5em;
	height: 8.5em;
	transform: translate(-90%,-50%);
	transition: transform var(--transDur) ease-in-out;
	z-index: 0;
}
.handle:before {
	background:
		radial-gradient(2em 1.5em at 50% 35%,#fff6 15%,#fff0),
		radial-gradient(1.5em 2.5em at 75% 40%,#fff6 15%,#fff0),
		radial-gradient(100% 100% at 50% 33%,#0000 25%,#0003 50%);
	border-radius: 50%;
	box-shadow: 0 0 0.3em 0.1em #0003 inset;
	content: "";
	display: block;
	position: absolute;
	top: 0;
	left: 0;
	width: 100%;
	height: 100%;
	z-index: 3;
}
.handle-off, .handle-on {
	width: 50%;
	height: 100%;
	transition: transform calc(var(--transDur)/2);
	z-index: 2;
}
.handle-off {
	background: var(--off);
	border-radius: 100% 0 0 100% / 50% 50% 50% 50%;
	right: 50%;
	transform-origin: 100% 50%;
	transition-delay: calc(var(--transDur)/2);
	transition-timing-function: ease-out;
}
.handle-on {
	background: var(--on);
	border-radius: 0 100% 100% 0 / 50% 50% 50% 50%;
	left: 50%;
	transform: scaleX(0);
	transform-origin: 0 50%;
	transition-timing-function: ease-in;
}

/* On */
input:checked + .toy-toggle .border3 {
	background-position: 25% 0;
}
input:checked + .toy-toggle .handle {
	transform: translate(-10%,-50%);
}
input:checked + .toy-toggle .handle-off {
	transform: scaleX(0);
	transition-delay: 0s;
	transition-timing-function: ease-in;
}
input:checked + .toy-toggle .handle-on {
	transform: scaleX(1);
	transition-delay: calc(var(--transDur)/2);
	transition-timing-function: ease-out;
}