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HTML 

              
                <div class="switch">
	<label class="switch__label" for="temperature-scale">Temperature</label>
	<button class="switch__button" type="button" id="temperature-scale" title="Temperature Scale" aria-labelledby="f">
		<span class="switch__button-wrap">
			<span class="switch__shadow"></span>
			<span class="switch__shadow"></span>
			<span class="switch__inner">
				<span class="switch__options">
					<span id="c" class="switch__option-label" aria-hidden="true">&deg;C</span>
					<span class="switch__option-sep"></span>
					<span id="f" class="switch__option-label" aria-hidden="true">&deg;F</span>
				</span>
			</span>
		</span>
	</button>
</div>
!

CSS 

              
                * {
	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;
	--trans-timing: cubic-bezier(0.65,0,0.35,1);
	font-size: calc(60px + (120 - 60) * (100vw - 280px) / (3840 - 280));
}
body,
button {
	font: 1em/1.5 "DM Sans", sans-serif;
}
body {
	background-color: var(--bg);
	color: var(--fg);
	display: flex;
	height: 100vh;
	transition:
		background-color var(--trans-dur),
		color var(--trans-dur);
}
.switch {
	display: flex;
	margin: auto;

	&__button,
	&__label {
		-webkit-tap-highlight-color: transparent;
	}
	&__button {
		background-color: transparent;
		border-radius: 0.75em;
		box-shadow: 0 0 0 0.125em hsla(var(--hue),90%,50%,0);
		cursor: pointer;
		outline: transparent;
		width: 100%;
		height: 100%;
		-webkit-appearance: none;
		appearance: none;
		z-index: 1;
		transition: box-shadow calc(var(--trans-dur) / 2);

		&:focus-visible {
			box-shadow: 0 0 0 0.125em hsla(var(--hue),90%,50%,1);
		}
		&,
		&-wrap {
			display: block;
			position: relative;
		}
		&-wrap {
			box-shadow:
				0 0.0625em 0.0625em hsl(var(--hue),10%,65%) inset,
				0 -0.0625em 0.0625em hsl(var(--hue),10%,87.5%) inset,
				0 0.25em 0.25em hsl(var(--hue),10%,70%) inset;
			border-radius: 0.75em;
			width: 3.1875em;
			height: 1.5em;
			transition: box-shadow var(--trans-dur);
		}
	}
	&__label {
		overflow: hidden;
		margin-inline-end: 0.75em;
		position: absolute;
		width: 1px;
		height: 1px;
	}
	&__inner,
	&__options,
	&__options:before,
	&__options:after,
	&__shadow {
		position: absolute;
	}
	&__inner,
	&__options {
		background-color: hsl(var(--hue),10%,90%);
	}
	&__inner {
		box-shadow: 0 -0.125em 0.25em hsl(var(--hue),10%,80%) inset;
		border-radius: 0.5em;
		display: block;
		perspective: 20em;
		inset: 0.25em;
		transition:
			background-color var(--trans-dur),
			box-shadow var(--trans-dur);
	}
	&__options {
		border-radius: inherit;
		box-shadow: 0 0 1px hsl(0,0%,100%) inset;
		display: flex;
		justify-content: space-around;
		font-size: 0.5em;
		line-height: 2;
		width: 100%;
		height: 100%;
		transform: translateX(-0.125rem) rotateY(-15deg);
		transition:
			background-color var(--trans-dur),
			box-shadow var(--trans-dur),
			transform var(--trans-dur) var(--trans-timing);

		&:before,
		&:after {
			content: "";
			display: block;
			top: 0;
			width: 45%;
			height: 100%;
			transition: opacity var(--trans-dur) var(--trans-timing);
		}
		&:before {
			border-radius: 0.5rem 0 0 0.5rem;
			box-shadow:
				0 1px 0.0625rem hsla(var(--hue),10%,10%,0.7) inset,
				0.125rem 0.25rem 0.25rem hsla(var(--hue),10%,10%,0.3) inset;
			mask-image: linear-gradient(-90deg,hsla(var(--hue),10%,90%,0),hsl(var(--hue),10%,90%));
			left: 0;
		}
		&:after {
			border-radius: 0 0.5rem 0.5rem 0;
			box-shadow:
				0 1px 0.0625rem hsla(var(--hue),10%,10%,0.7) inset,
				-0.125rem 0.25rem 0.25rem hsla(var(--hue),10%,10%,0.3) inset;
			mask-image: linear-gradient(90deg,hsla(var(--hue),10%,90%,0),hsl(var(--hue),10%,90%));
			right: 0;
			opacity: 0;
		}
	}
	&__option {
		&-label {
			color: var(--fg);
			font-weight: 500;
			text-align: center;
			width: 100%;
			text-shadow:
				0 -1px 0 hsl(var(--hue),10%,40%),
				0 1px 0 hsl(0,0%,100%);
			transition:
				color var(--trans-dur),
				text-shadow var(--trans-dur);

			&:last-child {
				color: hsl(var(--hue),10%,60%);
			}
		}
		&-sep {
			background-color: hsl(var(--hue),10%,75%);
			box-shadow: 1px 0 0 hsl(0,0%,100%);
			width: 1px;
			min-width: 1px;
			margin: auto 0;
			height: 0.75rem;
			transition:
				background-color var(--trans-dur),
				box-shadow var(--trans-dur);
		}
	}
	&__shadow {
		border-radius: 0.375em 0.875em 0.375em 0.375em / 0.375em 0.625em 0.125em 0.375em;
		box-shadow: 0 0 0 0.125em hsla(var(--hue),10%,10%,0.7);
		display: block;
		top: 0.375em;
		left: 0.375em;
		width: 1.25em;
		height: 0.75em;
		transform: rotate(0);
		transform-origin: 1em 0.375em;
		transition:
			box-shadow var(--trans-dur) var(--trans-timing),
			transform var(--trans-dur) var(--trans-timing);
		z-index: -1;
	}
	&__shadow + &__shadow {
		border-radius: 0.875em 0.375em 0.375em 0.375em / 0.625em 0.375em 0.375em 0.125em;
		box-shadow: 0 0 0.25em 0.125em hsla(var(--hue),10%,10%,0.7);
		right: 0.375em;
		left: auto;
		transform: rotate(7.5deg);
		transform-origin: 0.5em 0.375em;
	}
	&__button[aria-labelledby="f"] &__options {
		transform: translateX(0.125rem) rotateY(15deg);

		&:before {
			opacity: 0;
		}
		&:after {
			opacity: 1;
		}
	}
	&__button[aria-labelledby="f"] &__option-label {
		color: hsl(var(--hue),10%,60%);

		&:last-child {
			color: var(--fg);
		}
	}
	&__button[aria-labelledby="f"] &__shadow {
		box-shadow: 0 0 0.25em 0.125em hsla(var(--hue),10%,10%,0.7);
		transform: rotate(-7.5deg);
	}
	&__button[aria-labelledby="f"] &__shadow + &__shadow {
		box-shadow: 0 0 0 0.125em hsla(var(--hue),10%,10%,0.7);
		transform: rotate(0);
	}
}

/* Dark theme */
@media (prefers-color-scheme: dark) {
	:root {
		--bg: hsl(var(--hue),10%,30%);
		--fg: hsl(var(--hue),10%,90%);
	}
	.switch {
		&__button {
			box-shadow: 0 0 0 0.125em hsla(var(--hue),90%,70%,0);

			&:focus-visible {
				box-shadow: 0 0 0 0.125em hsla(var(--hue),90%,70%,1);
			}
			&-wrap {
				box-shadow:
					0 0.0625em 0.0625em hsl(var(--hue),10%,5%) inset,
					0 -0.0625em 0.0625em hsl(var(--hue),10%,27.5%) inset,
					0 0.25em 0.25em hsl(var(--hue),10%,20%) inset;
			}
		}
		&__inner,
		&__options {
			background-color: hsl(var(--hue),10%,30%);
		}
		&__inner {
			box-shadow: 0 -0.125em 0.25em hsl(var(--hue),10%,20%) inset;
		}
		&__options {
			box-shadow: 0 0 1px hsl(var(--hue),10%,50%) inset;
		}
		&__option {
			&-label {
				text-shadow:
					0 -1px 0 hsl(var(--hue),10%,10%),
					0 1px 0 hsl(var(--hue),10%,50%);
	
				&:last-child {
					color: hsl(var(--hue),10%,20%);
				}
			}
			&-sep {
				background-color: hsl(var(--hue),10%,20%);
				box-shadow: 1px 0 0 hsl(var(--hue),10%,50%);
			}
		}
		&__button[aria-labelledby="f"] &__option-label {
			color: hsl(var(--hue),10%,20%);
		}
		&__shadow
		&__button[aria-labelledby="f"] &__shadow + &__shadow {
			box-shadow: 0 0 0 0.125em hsla(var(--hue),10%,10%,0.9);
		}
		&__shadow + &__shadow,
		&__button[aria-labelledby="f"] &__shadow {
			box-shadow: 0 0 0.25em 0.125em hsla(var(--hue),10%,10%,0.9);
		}
	}
}
!

JS 

              
                window.addEventListener("DOMContentLoaded",() => {
	const rockerSwitch = new RockerSwitch("#temperature-scale");
});

class RockerSwitch {
	/** Button used for this switch */
	button: HTMLButtonElement | null;

	/**
	 * @param buttonEl CSS selector of the button to use
	 */
	constructor(buttonEl: string) {
		this.button = document.querySelector(buttonEl);
		this.button?.addEventListener("click",this.temperatureScaleToggle.bind(this));
	}
	private _temperatureScale: TemperatureScale = "f";
	/** Selected temperature scale */
	get temperatureScale(): TemperatureScale {
		return this._temperatureScale;
	}
	set temperatureScale(value: TemperatureScale) {
		this._temperatureScale = value;
		this.button?.setAttribute("aria-labelledby",this._temperatureScale);
	}
	/** Set the temperature scale to °C or °F. */
	temperatureScaleToggle(): void {
		this.temperatureScale = this.temperatureScale === "c" ? "f" : "c";
	}
}
type TemperatureScale = "c" | "f";
!
999px

Console