<div class="menu">

	<div class="menu-header">
		<h2 class="menu-header-title">Theme</h2>
		<div class="theme-switcher">
			<input type="radio" id="light-theme" name="themes" checked />
			<label for="light-theme">
				<span>
					<i data-feather="sun"></i>Light
				</span>
			</label>
			<input type="radio" id="dark-theme" name="themes" />
			<label for="dark-theme">
				<span>
					<i data-feather="moon"></i>Dark
				</span>
			</label>
			<input type="radio" id="black-theme" name="themes" />
			<label for="black-theme">
				<span>
					<i data-feather="star"></i>Black
				</span>
			</label>
			<span class="slider"></span>
		</div>
	</div>
	<div class="menu-body">
		<a href="#"><i data-feather="user"></i>Account Settings</a>
		<a href="#"><i data-feather="message-square"></i>Give Feedback</a>
		<a href="#"><i data-feather="info"></i>About</a>
		<a href="#"><i data-feather="life-buoy"></i>Support</a>
	</div>

</div>
@import url("https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap");

*,
*:after,
*:before {
	box-sizing: border-box;
}

:root {
	--c-text-primary: #191919;
	--c-text-secondary: #737374;
	--c-border-primary: #ccc;
	--c-bg-body: #ccc;
	--c-bg-primary: #fff;
	--c-bg-secondary: #d4d8dd;
	--c-bg-button: #fff;
	--slider-shadow: inset 0 1px 1px #ddd, 0 2px 3px #ccc;

	&.dark-theme {
		--c-text-primary: #eee;
		--c-text-secondary: #d3d5db;
		--c-border-primary: #454545;
		--c-bg-primary: #323339;
		--c-bg-secondary: #222128;
		--c-bg-button: #494a50;
		--slider-shadow: inset 0 1px 1px #767676;
	}

	&.black-theme {
		--c-text-primary: #edeeef;
		--c-text-secondary: #d4d7e1;
		--c-border-primary: #323232;
		--c-bg-primary: #1b1d23;
		--c-bg-secondary: #000001;
		--c-bg-button: #343844;
		--slider-shadow: inset 0 1px 1px #555;
	}
}

body {
	font-family: "Inter", sans-serif;
	line-height: 1.5;
	min-height: 100vh;
	display: flex;
	align-items: flex-end;
	justify-content: center;
	background-color: var(--c-bg-body);
	color: var(--c-text-primary);
}

.menu {
	width: 90%;
	max-width: 320px;
	background-color: var(--c-bg-primary);
	transition: background-color 0.15s ease;
	border-radius: 10px 10px 0 0;
	box-shadow: 0 0 2px rgba(#000, 0.05), 0 -4px 16px rgba(#000, 0.1);
}

.menu-header {
	padding: 1rem;
}

.menu-header-title {
	font-size: 0.875rem;
	color: var(--c-text-secondary);
	margin-bottom: 0.375rem;
	font-weight: 500;
}

.theme-switcher {
	background-color: var(--c-bg-secondary);
	border-radius: 10px;
	display: flex;
	padding: 0 3px;
	align-items: center;
	position: relative;
	overflow: hidden;
	.slider {
		display: block;
		position: absolute;
		z-index: 1;
		width: calc((100% - 6px) / 3);
		top: 3px;
		transform: translatex(-110%);
		bottom: 3px;
		border-radius: 6px;
		transition: 0.15s ease, transform 0.25s ease-out;
		background-color: var(--c-bg-button);
		box-shadow: var(--slider-shadow);
	}

	input {
		display: none;

		&:nth-of-type(1):checked ~ .slider {
			transform: translateX(0);
		}

		&:nth-of-type(2):checked ~ .slider {
			transform: translateX(100%);
		}

		&:nth-of-type(3):checked ~ .slider {
			transform: translateX(200%);
		}
	}
	label {
		position: relative;
		z-index: 2;
		width: calc(100% / 3);
		color: var(--c-text-secondary);

		span {
			padding: 8px 0;
			border-radius: 6px;
			display: flex;
			justify-content: center;
			align-items: center;
			font-weight: 500;
		}

		svg {
			display: inline-block;
			margin-right: 0.5rem;
			width: 20px;
		}
	}
}

.menu-body {
	display: flex;
	flex-direction: column;
	padding: 0.5rem;
	border-top: 1px solid var(--c-border-primary);
	transition: border-color 0.15s ease;

	a {
		text-decoration: none;
		color: inherit;
		display: flex;
		align-items: center;
		padding: 0.625rem 0.5rem;
		border-radius: 4px;
		font-weight: 500;
		transition: 0.15s ease;
		svg {
			margin-right: 1rem;
			color: var(--c-text-secondary);
			transition: color 0.15s ease;
		}

		&:hover {
			background-color: var(--c-bg-secondary);
		}
	}
}
View Compiled
feather.replace();

// Just a tiny bit of JavaScript to add classnames to the HTML-element on toggle
var html = document.getElementsByTagName('html');
var radios = document.getElementsByName('themes'); 

for (i = 0; i < radios.length; i++) {
	radios[i].addEventListener('change', function() {
	  html[0].classList.remove(html[0].classList.item(0));
		html[0].classList.add(this.id);
	});
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://unpkg.com/feather-icons