黑白切换按钮

 <style type="text/css">
* {
	border: 0;
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
:root {
	--dur: 0.3s;
	font-size: calc(40px + (80 - 40)*(100vw - 320px)/(2560 - 320));
}
body, input {
	color: hsl(0,0%,10%);
	font: 1em/1.5 sans-serif;
}
form, .toggle:before, .toggle:after {
	background: hsl(0,0%,90%);
}
form, .toggle {
	position: relative;
}
form {
	display: flex;
	justify-content: center;
	align-items: center;
	height: 100vh;
}
.curtain, .sr, .toggle:before, .toggle:after {
	position: absolute;
}
.curtain, .toggle:before, .toggle:after {
	transition: transform var(--dur);
}
.curtain, .toggle:before, .toggle:checked:after  {
	transition-timing-function: ease-out;
}
.curtain, .sr {
	top: 0;
	left: 0;
}
.curtain {
	background: hsl(0,0%,100%);
	mix-blend-mode: difference;
	pointer-events: none;
	width: 100%;
	height: 100%;
	transform: scaleX(0);
	transform-origin: 0 50%;
}
.sr, .toggle {
	overflow: hidden;
}
.sr {
	clip: rect(1px,1px,1px,1px);
	color: transparent;
	width: 1px;
	height: 1px;
}
.toggle {
	background: currentColor;
	border-radius: 0.75em;
	cursor: pointer;
	width: 3em;
	height: 1.5em;
	-webkit-appearance: none;
	appearance: none;
	-webkit-tap-highlight-color: transparent;
}
.toggle:before, .toggle:after {
	border-radius: 50%;
	content: "";
	display: block;
	top: 0.25em;
	left: 0.25em;
	width: 1em;
	height: 1em;
}
.toggle:before, .toggle:checked:after {
	transition-delay: 0s;
}
.toggle:checked:before, .toggle:after {
	transition-delay: calc(var(--dur) * 0.75);
	transition-timing-function: cubic-bezier(0.3,1.6,0.5,0.7);
}
.toggle:before {
	transform: translateX(-1.5em);
}
.toggle:checked:before {
	transform: translateX(1.5em);
}
.toggle:checked:after {
	transform: translateX(3em);
}
.toggle:checked ~ .curtain {
	transform: scaleX(1);
}
.toggle:focus {
	outline: transparent;
}
</style>
<form>
	<input id="dark-mode" class="toggle" type="checkbox" name="Dark mode" role="switch" value="on">
	<label for="dark-mode" class="sr">Dark Mode</label>
	<div class="curtain"></div>
</form>