- let min = 1, max = 5, val = min;

body(style=`--b: ${val}`)
	form
		label(for='b') blur amount
		input#b(type='range' min=min value=val max=max step='.5')
		output(for='b') contrast(16) blur(#{val}px) contrast(#{2.5*val})
View Compiled
html {
	height: 100%;
	--pattern: 
		repeating-conic-gradient(
				#777, #fff, #777 2.5%);
	--map: linear-gradient(90deg, #888, #fff);
	background: var(--pattern), var(--map);
	background-blend-mode: multiply
}

body {
	margin: 0;
	backdrop-filter: contrast(16) 
		blur(calc(var(--b)*.5px)) 
		contrast(calc(2.5*var(--b)))
}

/* prettifying controls & stuff */
$track-h: 6px;
$track-r: .5*$track-h;

$thumb-d: 1em;
$thumb-r: .5*$thumb-d;

@mixin track() {
	height: $track-h;
	border-radius: $track-r;
	background: dimgrey;
}

@mixin thumb($f: 0) {
	@if $f > 0 {
		margin-top: calc(#{$track-r} + -1*#{$thumb-r})
	}
	
	border: 0;
	width: $thumb-d; height: $thumb-d;
	border-radius: 50%;
	background: currentcolor;
	cursor: ew-resize
}

* { margin: 0; color: inherit; font: inherit }

html, body, form { display: grid }

form {
	box-sizing: border-box;
	place-self: end center;
	margin: .5em;
	width: Min(22.5em, 100%);
	padding: .5em;
	background: #370617;
	color: #ededed;
	font: clamp(.75em, 4vw, 1.25em) sans-serif
}

label {
	justify-self: center;
	
	&::after { content: ':' }
}

[type='range'] {
	&, &::-webkit-slider-thumb { appearance: none }
	
	--hov: 0;
	width: 100%; height: $thumb-d;
	background: #0000;
	color: #f7b538;
	filter: Saturate(var(--hov));
	transition: filter .35s ease-out;
	cursor: pointer;
	
	&::-webkit-slider-runnable-track { @include track }
	&::-moz-range-track { @include track }
	&::slider-track { @include track }
	
	&::-webkit-slider-thumb { @include thumb(1) }
	&::-moz-range-thumb { @include thumb }
	&::slider-thumb { @include thumb }
	
	&:focus { outline: none }
	
	&:is(:hover, :focus) { --hov: 1 }
}

output {
	font: .875em monospace
}
View Compiled
addEventListener('input', e => {
	let _t = e.target, v = +_t.value;
		
	document.body.style.setProperty(`--${_t.id}`, v)
	_t.nextElementSibling.textContent = `contrast(16) blur(${v}px) contrast(${2.5*v})`
})

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