2 CSS if() Real-World Examples for Clean Stylesheets

css by Vladimir 1 min read

Conditional value assignment inside CSS properties historically required duplicating entire selector blocks across media or container queries. The inline if() specification shifts decision-making down to the individual property level, allowing stylesheets to calculate dynamic values based on media contexts, style queries, and registered variables on a single line.

  • Branching logic resolves directly within the browser’s computed-value pipeline, evaluating conditions before paint operations execute.
  • Binding inline conditional expressions with local style queries preserves semantic integrity, eliminating class-name pollution in the DOM.
  • Offloading value selection from main-thread JavaScript to native style calculation reduces architectural overhead and protects rendering frame rates.

Adopting inline value logic transforms static property declarations into self-contained, reactive style rules.

Table of Contents:

  1. Examples
  2. Frequently Asked Questions

Examples

Cyberpunk theme switcher using CSS corner-shape notches, light-dark colors, and pure CSS state handling.

Futuristic CSS Theme Switcher with Corner Shaping

A pure CSS theme switcher showcasing bleeding-edge spec features. Uses :has() on :root to toggle color schemes without JavaScript. Leverages light-dark(), color-mix(), and native inline if() logic for dynamic styling. Corner shapes like notch and superellipse() provide a pixel-art sci-fi aesthetic. Built on an accessible <fieldset> radio control structure with full keyboard focus support.

Technologies:
HTML CSS
Difficulty:Advanced
Browser Support (as of Jul 2026):
Chrome Chrome Edge Edge
Features:
Pure CSS State Corner Shaping Color Mix Engine Inline CSS if()
Bundle Size / GPU Accelerated4 kB / Yes
Use Cases:Dark Themes, Futuristic Dashboards, Gaming UI
Code by: Mandy Nicole Mandy Nicole
License: MIT
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<fieldset id="color-scheme">
  <legend>Theme</legend>
  <label for="system" tabindex="0">
    <input type="radio" id="system" name="theme" value="system" tabindex="-1"/><span>Sys</span>
  </label>
  <label for="light" tabindex="0">
    <input type="radio" id="light" name="theme" value="light" tabindex="-1" checked="checked"/><span>Light</span>
  </label>
  <label for="dark" tabindex="0">
    <input type="radio" id="dark" name="theme" value="dark" tabindex="-1"/><span>Dark</span>
  </label>
</fieldset>

fieldset {
	border: 2px solid 
		if(
			style(--color-scheme: light):
				color-mix(
					in oklab, 
					var(--theme-accent), 
					transparent 80%
				)
			;
			
			/* uses NOT over ELSE to respect `prefers-color-scheme` */
			not style(--color-scheme: light): 
				color-mix(
					in oklab, 
					var(--theme-accent), 
					transparent 70%
				)
			;
		)
	;	
	border-radius: 5px;
	corner-shape: notch;
	color: var(--theme-text);
	outline: 
		7px ridge 		
		if(
			style(--color-scheme: light):
				color-mix(
					in oklab, 
					var(--theme-accent), 
					transparent 25%
				)
			;
			
			/* uses NOT over ELSE to respect `prefers-color-scheme` */
			not style(--color-scheme: light): 
				color-mix(
					in oklab, 
					var(--theme-accent), 
					transparent 25%
				)
			;
		)
	;	
	outline-offset: 2px;
	
	filter: 
		drop-shadow(
			0 0 1dvw 
			color-mix(
				in oklab, 
				light-dark(	transparent, var(--theme-accent) ), 
				transparent 5%
			)
		)
		drop-shadow(
			0 0 5dvw 
			color-mix(
				in oklab, 
				light-dark(	transparent, var(--theme-accent) ), 
				transparent 25%
			)
		)
	;
	
	font-family: "Silkscreen", monospace;	
	font-size: 1.75rex;
	letter-spacing: -.075ch;
	text-rendering: geometricprecision;
	
	display: grid;
	gap: 0;
	
	margin: 0;
	padding: 0;
	
	max-width: 30px;
	padding: 6px 12px;
	
	position: relative;
	z-index: 3;
	
	legend {
		color: color-mix(in oklab, var(--theme-accent), transparent 25%);
		text-align: center;
		text-box: trim-both cap alphabetic;
		top: -.5ex;
		position: relative;
		padding-top: .84ex;
	}
}

input {
	--d: 10px;
	--rotation: 225deg;
	
	appearance: none;
	
	background: currentColor;
	color: inherit;
	
	border-radius: 6px;
	corner-shape: notch;
	rotate: var(--rotation);
	
	margin-top: -1px;
	
	outline: 2px solid color-mix(in oklab, var(--theme-text), transparent 50%);
	outline-offset: 2px;
	
	height: var(--d);
	width: var(--d);

	label:hover &:not(:checked) {
		--rotation: 90deg;
		corner-shape: superellipse(-.25);
		outline-color: color-mix(in oklab, var(--theme-text), transparent 75%);
	}
	
	&:checked {		
		--rotation: unset;
		color: inherit;
		outline-color: color-mix(in oklab, var(--theme-accent), transparent 25%);
		outline-offset: 3px;
		corner-shape: superellipse(-.5);
		
		label:hover & {
			outline-color: color-mix(in oklab, var(--theme-accent), transparent 0%);
		}
	}
}

label {
	border-radius: 6px;
	corner-shape: superellipse(-1);
	
	display: flex;
	align-items: center;
	gap: 8px;	
	
	user-select: none;
	padding: 19px 24px 18px;
	
	span {
		text-box: trim-both cap alphabetic;
		display: inline-block;
	}
	
	&:has(:checked) {		
		background: var(--theme-text);		
		color: var(--theme-canvas);
		
		input { color: var(--theme-accent);	}
	}
	
	&:is(:focus-visible),
	&:has(:focus-within) {
		--rotation: 225deg;
		outline-width: 2px;
		outline-style: solid;
		outline-offset: -4px;
	}
	
	&:is(:focus-visible) {
		outline-color: color-mix(in oklab, var(--theme-accent), transparent 50%);
		&:not(:has(:checked)):hover { background: color-mix(in oklab, var(--theme-accent), transparent 84%); }
	}
	
	&:has(:focus-within) {
		outline-color: color-mix(in oklab, var(--theme-accent), transparent 50%);
	}
	
	&:has(:focus) {
		outline-color: color-mix(in oklab, var(--theme-accent), transparent 50%);
	}
}

@media (prefers-reduced-motion: no-preference) {		
	html,
	body,
	fieldset, 
	label, 
	input { 
		transition-property: background, border-color, box-shadow, color, filter, rotate;
		transition-duration: .2s;
		transition-timing-function: ease-out;
	}
	
	label,
	input {
		&:focus-within,
		&:focus,
		&:hover,
		&:focus-visible {
			transition-property: background, border-color, rotate;
			transition-duration: .2s;
			transition-timing-function: ease-in;
		}
	}
}

:root {
	--white: 0 0 90%;
	--black: 0 0 10%;
	--gray: 0 0 45%;
	
	--gold: 36deg 75% 33%;
	--turq: 150deg 55% 35%;
	
	--theme-canvas: light-dark(
		hsl(var(--white)),
		hsl(var(--black))
	);
	
	--theme-text: light-dark(
		hsl(var(--black)),
		hsl(var(--white))
	);
	
	--theme-text-2: ;
	
	--theme-accent: light-dark(
		hsl(var(--gold)),
		hsl(var(--turq))
	);
	
	--color-scheme: light dark;
	color-scheme: var(--color-scheme);
	&:has(#color-scheme input[value="light"]:checked) {	--color-scheme: light; }
	&:has(#color-scheme input[value="dark"]:checked) { --color-scheme: dark; }
	
	container: html / inline-size;
}

@font-face {
	src: url("https://assets.codepen.io/2392/Silkscreen-Regular.woff2");
	font-family: "Silkscreen";
}
	
body {
	accent-color: var(--theme-accent);
	background: var(--theme-canvas);	
	color: var(--theme-text);
	
	box-sizing: border-box;
	display: grid;
	place-content: center;	
	
	height: 100cqh;	
	margin: 0;
	padding: 3rem 3cqw;	
}
  • Colors & Palette: Redefine --gold (36deg 75% 33%), --turq (150deg 55% 35%), or override --theme-accent and --theme-canvas inside :root using custom hsl() coordinates.
  • Corner Geometry: Replace corner-shape: notch or corner-shape: superellipse(-.5) on fieldset and input selectors to alter edge geometry.
  • Switch Sizing: Adjust --d: 10px on input to rescale input indicators, or tweak padding: 19px 24px 18px on label for custom panel height.
  • Typography: Swap font-family: "Silkscreen", monospace and font-size: 1.75rex on fieldset to change retro text rendering.
  • Glow & Shadow Effects: Modify drop-shadow() parameters and color-mix() opacity percentages on fieldset to control light-dark background halos.
  • Rotation Angles: Alter --rotation: 225deg on input to change indicator hover transformation direction.
Responsive portfolio project grid featuring holographic background overlays, container query cards, and stacked image previews.

Holographic CSS Project Cards Grid

An advanced portfolio project card layout leveraging CSS Container Queries and modern color functions. Features dynamic light/dark/holo theme switching using :has() selectors and @property animated radial gradients. Staggered card preview stacks expand on hover with pure CSS if() media logic and mix-blend-mode effects. Semantic layout powered by CSS Grid.

Technologies:
HTML CSS
Difficulty:Advanced
Browser Support (as of Jul 2026):
Chrome Chrome Edge Edge
Features:
Holographic Overlay Container Queries Pure CSS Theme Stacked Previews
Bundle Size / GPU Accelerated9 kB / Yes
Use Cases:Portfolio Web, Showcases, Agency Landing Pages
Code by: Mandy Nicole Mandy Nicole
License: MIT
Loading...
<header class="settings">
  <fieldset id="color-scheme">
    <label for="system" tabindex="0">
      <input id="system" type="radio" name="theme" value="system" checked="checked"/>				<span>Sys</span>
    </label>
    <label for="light" tabindex="0">
      <input id="light" type="radio" name="theme" value="light"/>				<span>Light</span>
    </label>
    <label for="dark" tabindex="0">
      <input id="dark" type="radio" name="theme" value="dark"/>				<span>Dark</span>
    </label>
    <label for="holo" tabindex="0">
      <input id="holo" type="checkbox" name="theme" value="holo" checked="checked"/>				<span>Holo</span>
    </label>
  </fieldset>
</header>
<div class="project-container">
  <div class="project project--3 full">
    <div class="preview-container">
      <picture tabindex="0">
        <div class="bg red" alt="fakeCap"></div>
      </picture>
      <picture tabindex="0">
        <div class="bg blue" alt="fakeCap"></div>
      </picture>
      <picture tabindex="0">
        <div class="bg green" alt="fakeCap"></div>
      </picture>
    </div>
    <div class="content-container">
      <hgroup>
        <h1>Project / Client Name</h1>
        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p>
      </hgroup>
      <ul class="tag-container">
        <li class="tag design">ui/ux</li>
        <li class="tag design">component library</li>
        <li class="tag design">product design</li>
        <li class="tag dev">interactive prototypes</li>
        <li class="tag dev">html</li>
        <li class="tag dev">css</li>
        <li class="tag dev">documentation</li>
      </ul>
    </div>
  </div>
  <div class="project project--1">
    <div class="preview-container">
      <picture tabindex="0">
        <div class="bg green" alt="fakeCap"></div>
      </picture>
      <picture tabindex="0">
        <div class="bg red" alt="fakeCap"></div>
      </picture>
      <picture tabindex="0">
        <div class="bg blue" alt="fakeCap"></div>
      </picture>
    </div>
    <div class="content-container">
      <hgroup>
        <h1>Project / Client Name</h1>
        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p>
      </hgroup>
      <ul class="tag-container">
        <li class="tag design">ui/ux</li>
        <li class="tag design">component library</li>
        <li class="tag design">a11y auditing</li>
        <li class="tag design">wcag conformance</li>
        <li class="tag dev">interactive prototyping</li>
        <li class="tag dev">html</li>
        <li class="tag dev">css</li>
        <li class="tag dev">documentation</li>
      </ul>
    </div>
  </div>
  <div class="project project--2">
    <div class="preview-container">
      <picture tabindex="0">
        <div class="bg blue" alt="fakeCap"></div>
      </picture>
      <picture tabindex="0">
        <div class="bg green" alt="fakeCap"></div>
      </picture>
      <picture tabindex="0">
        <div class="bg red" alt="fakeCap"></div>
      </picture>
    </div>
    <div class="content-container">
      <hgroup>
        <h1>Project / Client Name</h1>
        <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</p>
      </hgroup>
      <ul class="tag-container">
        <li class="tag design">ui/ux</li>
        <li class="tag design">component library</li>
        <li class="tag design">wcag conformance</li>
        <li class="tag dev">interactive prototyping</li>
        <li class="tag dev">html</li>
        <li class="tag dev">css</li>
        <li class="tag dev">documentation</li>
      </ul>
    </div>
  </div>
</div>

@property --1-holo-pos {
  syntax: "<percentage>+";
  inherits: true;
  initial-value: 100% 0%;
}

@property --2-holo-pos {
  syntax: "<percentage>+";
  inherits: true;
  initial-value: 0% 100%;
}

:root {
	--scheme-light: light;
	--scheme-dark: dark;
	--color-scheme: var(--scheme-light) var(--scheme-dark);	
	color-scheme: var(--color-scheme);
	
	--primary--h: 25;
	--primary--s: 30%;
	--primary--l: 50%;
	
	--primary-000: var(--primary--h) var(--primary--s) 2.5%;	
	--primary-005: var(--primary--h) var(--primary--s) 6%;
	--primary-010: var(--primary--h) var(--primary--s) 12%;
	--primary-020: var(--primary--h) var(--primary--s) 20%;
	--primary-030: var(--primary--h) var(--primary--s) 30%;
	--primary-040: var(--primary--h) var(--primary--s) 40%;
	--primary-050: var(--primary--h) var(--primary--s) 50%;
	--primary-060: var(--primary--h) var(--primary--s) 60%;
	--primary-080: var(--primary--h) var(--primary--s) 80%;
	--primary-070: var(--primary--h) var(--primary--s) 70%;
	--primary-090: var(--primary--h) var(--primary--s) 90%;
	
	--secondary--h: 206;
	--secondary--s: 12%;
	--secondary--l: 50%;
	
	--secondary-000: var(--secondary--h) var(--secondary--s) 2.5%;	
	--secondary-005: var(--secondary--h) var(--secondary--s) 6%;
	--secondary-010: var(--secondary--h) var(--secondary--s) 12%;
	--secondary-020: var(--secondary--h) var(--secondary--s) 20%;
	--secondary-030: var(--secondary--h) var(--secondary--s) 30%;
	--secondary-040: var(--secondary--h) var(--secondary--s) 40%;
	--secondary-050: var(--secondary--h) var(--secondary--s) 50%;
	--secondary-060: var(--secondary--h) var(--secondary--s) 60%;
	--secondary-080: var(--secondary--h) var(--secondary--s) 80%;
	--secondary-070: var(--secondary--h) var(--secondary--s) 70%;
	--secondary-090: var(--secondary--h) var(--secondary--s) 90%;
	
	--bg: light-dark( hsl(var(--primary-080)), hsl(var(--secondary-010)) );
	
	--spacer-x: 1.75dvw;
	--spacer-y: 18px;
	
	--spacer: min(var(--spacer-x), var(--spacer-y));
	
	--radius-min: 3cqi;
	--radius-001: min(var(--radius-min), 18px);
	--radius-002: calc( var(--radius-001) / 2 );	
}

.project-container {
	--col-w--min: calc(max(390px, 50cqw) - var(--spacer-x));
	
	container: project-container / inline-size;	
	display: grid;
	grid-template-columns: 
		repeat(
			auto-fit, 
			minmax( min( var(--col-w--min), 100% ), 1fr )
		)
	;
	gap: calc(var(--spacer-y) * 2) var(--spacer-x);
	margin: 0 auto;
}

.project {	
	--preview-x: var(--x-init);
	
	background: 
		linear-gradient(
			light-dark( hsl(var(--primary-090) / .5), hsl(var(--secondary-020) / 1) ),
			light-dark( hsl(var(--primary-090) / 1), hsl(var(--secondary-040) / 1) )
		)
	;
	border-radius: var(--radius-001);
	
	container: project / inline-size;	
	
	display: grid;
	grid-template-rows: auto 1fr;
	align-content: start;
	min-height: 50cqh;
	
	&:not(.full) {
		--x-init: 6cqw;
		--x-hover: -1cqw;
		
		.preview-container {			
			picture {
				aspect-ratio: 9/16;
				height: 100cqh;
				
				&:nth-of-type(2) {
					height: 110cqh;
				}
			}
		}
	}
	
	&.full { 
		--x-init: 2cqw;
		--x-hover: -4cqw;
		grid-column: 1 / -1;
		
		.preview-container {			
			picture {
				aspect-ratio: 16/9;
				height: 100cqh;
				
				&:nth-of-type(2) {
					height: 110cqh;
					width: 75%;
					position: absolute;
				}
			}
		}
	}	
}

.preview-container {	
	border-radius: var(--radius-002);
	
	container: preview-container / size;	
	
	display: flex;
	align-items: center;
	justify-content: center;
	
	margin: var(--spacer) var(--spacer) 0 var(--spacer);
	padding: calc(var(--spacer) / 3);	
	
	min-height: 150px;
	height: 60cqw;
	max-height: 60dvh;
	
	transition-property: height;
	transition-duration: .3s;
	transition-timing-function: ease-out;

	will-change: height;
	
	position: relative;

	&:before {		
		background: linear-gradient(
			light-dark( hsl(var(--primary-070)), hsl(var(--secondary-010) / .75) ),
			light-dark( hsl(var(--primary-080) / .5), hsl(var(--secondary-020) / .35) )
		);
		
		border-bottom: 
			1px 
			solid 
			light-dark( 
				hsl(var(--primary--h) var(--primary--s) 95% / 1),  
				hsl(var(--secondary-060) / .45) 
			)
		;	
		border-radius: inherit;		
		opacity: 1;
		
		content: "";
		inset: 0;
		position: absolute;
	}
	
	picture {
		--height-init: 100cqh;
		--height: var(--height-init);
		--shadow-blur: 4cqw;
		--shadow-spread: 0;
		--shadow-y: .25cqh;
		--translateY: 1.25cqh;
		
		border-radius: var(--radius-002);			
		box-shadow: 
			0 
			var(--shadow-y)
			var(--shadow-blur) 
			var(--shadow-spread)
			
			if(
				style(--color-scheme: var(--scheme-light)): hsl( var(--primary-020) / var(--shadow-opacity, 60%) );
				not style(--color-scheme: var(--scheme-light)): hsl( var(--secondary-010) / var(--shadow-opacity, 75%) );
			)
		;
		
		container: picture / size;
		display: grid;
		place-content: start;	
		min-height: 0;
		
		overflow: hidden;
		
		translate: var(--translateX, 0) var(--translateY);
		
		transition-property: box-shadow, filter, opacity, rotate, translate, width;
		transition-duration: .3s;
		transition-timing-function: ease-in-out;
		
		position: relative;		
		
		/* stack <picture> contents */
		* { grid-area: 1 / 1;	}
		
		img {			
			border-radius: inherit;
			pointer-events: none;
			user-select: none;
			width: 100cqw;
			
			&.fill {
				all: initial;
				object-fit: cover;
			}
		}
		
		.project:has(:hover, :focus) & {
			--preview-x: var(--x-hover);
			
			--shadow-blur: 25cqh;
			--shadow-spread: 3cqh;
			--shadow-opacity: if(
					style(--color-scheme: var(--scheme-light)): 70%;
					not style(--color-scheme: var(--scheme-light)): 100%;
				)
			;
			filter: unset;
			mix-blend-mode: unset;
		}
		
		/* inactive state */
		.preview-container:has(:hover) &:not(:hover),
		&:first-of-type,
		&:last-of-type {
			mix-blend-mode: luminosity;
			filter: 
				grayscale(100%)
				if(
					style(--color-scheme: var(--scheme-light)): opacity(50%);
					not style(--color-scheme: var(--scheme-light)): brightness(60%) opacity(80%);
				)
			;
			
			&:focus,
			&:hover {
				filter: unset;
				mix-blend-mode: unset;
				opacity: 1;
				rotate: 0deg;
				z-index: 600;
			}
		}
		
		&:nth-of-type(1) {
			--translateX: var(--preview-x);
			rotate: if(
				media(width > 750px): -3deg; 
				media(width > 480px): -2deg; 
				else: 0deg
			);			
		}
		
		&:nth-of-type(2) {
			--translateY: -1.25cqh;
			scale: 1;
			z-index: 500;
			
			&:hover {
				--translateY: -2cqh;
			}
		}
		
		&:nth-of-type(3) {
			--translateX: calc(var(--preview-x) * -1);
			rotate: if(
				media(width > 750px): 3deg; 
				media(width > 480px): 2deg; 
				else: 0deg
			);
		}
		
		&:focus { 
			outline: 6px solid #ffc32c; 
			outline-offset: 3px; 
		}
		
		&.scrollable {
			cursor: ns-resize;			
			overflow-y: auto;
			scrollbar-width: none;
		}
		
		&:focus,
		&:hover {			
			--shadow-blur: 15cqh;
			--shadow-spread: 1cqh;
			--shadow-opacity: 50%;
			--shadow-y: 3cqh;
			--translateY: 0;
			mix-blend-mode: initial;
		}
	}
}

@media (orientation: portrait) {
	.preview-container {
		max-height: 360px;
	}
}

@media (max-width: 880px) {
	.preview-container {
		max-height: 720px;
	}
}

.content-container {
	display: grid;
	gap: 1lh;
	color: light-dark( hsl(var(--primary-030)), hsl(var(--secondary-080) / 1) );
	padding: 3ex min(6%, calc(var(--spacer) * 3));
	
	hgroup {
		display: grid;
		gap: .5ex;
		margin-block: .5ex;
		
		h1 {
			color: light-dark( hsl(var(--primary-010)), hsl(var(--secondary--h) var(--secondary--s) 95% / 1) );
			font-size: clamp(1.1rem, 5cqw, 1.5rem);
			font-weight: 550;
		}
		
		p { 
			font-size: clamp(0.85rem, 5cqw, 1rem);
			font-weight: 460;
			line-height: 2.4ex;
		}
	}
}

.tag-container {
	display: flex;
	flex-wrap: wrap;
	gap: .5ch;
	list-style: none;
	
	li.tag {
		border-radius: 60px;
		background: linear-gradient(
			light-dark( hsl(var(--primary-030) / .2), hsl(var(--secondary-020) / .81) ),
			light-dark( hsl(var(--primary-040) / .05), hsl(var(--secondary-020) / .36) )
		);
		
		border-bottom: 
			1px 
			solid 
			light-dark( 
				hsl(var(--primary--h) var(--primary--s) 95% / 1),  
				hsl(var(--secondary-060) / .65) 
			)
		;	
		
		display: flex;
		align-items: center;
		text-box: trim-both ex alphabetic;
		font-size: 84%;
		font-weight: 500;
		height: 29px;
		padding-inline: 1.45ch;
		padding-bottom: .18ex;
		user-select: none;
		white-space: nowrap;
		overflow-x: hidden;
		text-overflow: ellipsis;
	}
}

/* Demo Resets */
* { font-family: inherit; margin: 0; padding: 0; }

html { 
	background: var(--bg); 
	height: 100%;
	transition: all .45s ease-out;
	
	&:has(#color-scheme input[value="dark"]:checked) {
		--color-scheme: var(--scheme-dark);
	}

	&:has(#color-scheme input[value="light"]:checked) {
		--color-scheme: var(--scheme-light);
	}
	
	&:has(#color-scheme input[value="holo"]:checked) {
		body {
			&:before {
				background: 
					radial-gradient(
						circle at var(--1-holo-pos) in hsl longer hue,
						oklch(100% 0 80 / .75),
						oklch(90% 0.1 300 / .75)
					),
					radial-gradient(
						circle at var(--2-holo-pos) in hsl longer hue,
						oklch(90% 0.1 70 / .75),
						oklch(90% 0.1 370 / .75)
					),
					radial-gradient(
						rgba(168, 169, 174), 
						rgba(165, 174, 216)
					)		
				;
				background-blend-mode: plus-lighter, plus-darker, overlay;
				animation-name: holo-anim;
				animation-duration: 3s;
				animation-iteration-count: infinite;
				animation-timing-function: ease-in-out;
				animation-direction: alternate;
				mix-blend-mode: color;
				opacity: .5;
				user-select: none;
				pointer-events: none;
				position: absolute;
				inset: 0;
				content: "";
				z-index: 10;
			}
		}
	}
}

body {
	container: body / inline-size;
	font-family: "Libre Franklin";
	padding: 0 calc(var(--spacer-x) * 4) calc(var(--spacer-y) * 4);
	overflow-x: hidden;
	position: relative;
}

@keyframes holo-anim {
	to { 
		--1-holo-pos: -50% 30%;
		--2-holo-pos: 60% 150%;
	}
}

header.settings {
	--header-border--w: 1px;
	border-radius: var(--radius-002);
	corner-shape: square square round round;
	overflow: clip;
	display: grid;
	justify-content: end;
	margin-bottom: calc(var(--spacer-y) * 3);	
	background: light-dark(
		hsl(var(--primary-070) / .5),
		hsl(var(--secondary-005) / .5)
	);
	color: light-dark(
		hsl(var(--primary-090)), 
		hsl(var(--secondary-010))
	);
	
	fieldset {
		border: 0;
		margin: 0;
		padding: 0;
	}

	label {
		cursor: pointer;
		display: flex;
		align-items: center;
		font-weight: 720;
		user-select: none;
	}
}

fieldset[id="color-scheme"] {
	display: flex;
	flex-wrap: wrap;

	label {
		--gap: 1.25ch;
		color: light-dark(
			hsl(var(--primary-030) / 0.75),
			hsl(var(--secondary-060) / 0.75)
		);			
		flex: 1;
		font-size: 1.25ex;
		margin: 0;
		padding: 3ex 1.5rem;
		text-transform: uppercase;

		input {
			color: inherit;
			appearance: none;
			border-radius: 2px;
			outline: 2px solid currentColor;		
			outline-offset: 2px;
			height: 0.5rem;
			width: 0.5rem;
			transition-property: outline, background;
			transition-duration: .15s;
			transition-timing-function: ease-out;

			&:checked {
				background: light-dark(
					hsl(var(--primary-060)),
					hsl(var(--secondary-010))
				);
				outline-color: light-dark(
					hsl(var(--primary-060) / .5),
					hsl(var(--secondary-010) / .5)
				);
			}
		}
		
		span {
			margin-left: 0.75rem;
		}

		&:hover {
			background: light-dark(
				hsl(var(--primary-090)),
				hsl(var(--secondary-010))
			);
			color: light-dark(
				hsl(var(--primary-040)),
				hsl(var(--secondary-090))
			);

			input {
				outline-color: currentColor;
				&:checked {
					background: currentColor;
				}
			}
		}

		&:has(input:checked) {
			background: light-dark(
				hsl(var(--primary-090)),
				hsl(var(--secondary-050))
			);
			color: light-dark(
				hsl(var(--primary-030)),
				hsl(var(--secondary-010))
			);
		}
		
		&[for="holo"] {
			--icon-unchecked: "✧";
			--icon-checked: "✦";
			--icon-opacity: .5;
			position: relative;
			
			input {				
				outline: 0;
				border: 0;
				width: 0;
			}

			span {
				margin-left: 1.15rem;
				&:before { 
					content: var(--icon, var(--icon-unchecked)); 
					font-size: 1.2rem;
					opacity: var(--icon-opacity);
					position: absolute;
					left: 1.5ch;
					top: .75ex;
				}					
			}

			&:has(:checked) {
				--icon: var(--icon-checked);
				--icon-opacity: 100%;
				input { background: none; }
			}
		}
	}
}

.bg {
	height: 100cqh;
	width: 100cqw;
}

.red { background: oklch(60% 50% 10deg); }
.blue { background: oklch(50% 60% 220deg); }
.green { background: oklch(70% 70% 110deg); }

@font-face {
	font-family: "Libre Franklin";
	src: url("https://assets.codepen.io/2392/LibreFranklin.ttf");
	font-style: normal;
	font-weight: 100 900;
}
  • Colors / Themes: Tweak base HSL color channels --primary--h: 25 and --secondary--h: 206 on :root. Customize preview card background blocks using .red, .blue, and .green selectors with custom oklch() values.
  • Gradients & Visual Effects: Edit the animated holographic foil overlay inside html:has(#color-scheme input[value="holo"]:checked) by altering radial-gradient stops and @keyframes holo-anim targets --1-holo-pos: -50% 30%. Adjust image card stack blending via mix-blend-mode: luminosity.
  • Sizing, Layout & Scales: Modify responsive grid column width --col-w--min: calc(max(390px, 50cqw) - var(--spacer-x)) on .project-container. Customize image stack fan-out distance by changing --x-init: 6cqw and --x-hover: -1cqw on .project.

Frequently Asked Questions

How does if() change the way developers write responsive utility rules?

Instead of writing three separate @media blocks to change a single value across breakpoints, if() allows wrapping those conditions inline inside one property (e.g., margin: if(media(min-width: 800px): 2rem; else: 1rem)). This dramatically reduces CSS file size and keeps component logic centralized rather than scattered across the file.

What occurs under the hood when the browser parses an if() expression?

The browser’s C++ style engine parses the condition during the computed-value phase of style recalculation. It evaluates the boolean check against the current environment context, selects the matching branch, and discards the unused value before the tree is passed to the painting engine, guaranteeing zero layout shifts.

Can if() evaluate custom property values registered with @property?

Yes. You can construct style queries inside if(), such as checking if(style(--theme: dark): #fff; else: #000). This enables custom design tokens to automatically toggle their internal child properties without requiring utility classes or JavaScript observer callbacks.

How does native if() logic benefit Interaction to Next Paint (INP) scores?

By shifting conditional styling logic away from JavaScript click or resize handlers, the main thread remains unblocked during user interactions. The browser handles value swapping internally in native compiled code, which prevents script-driven layout latency and ensures fast input responsiveness.

What is the recommended strategy when targeting browsers without if() support?

Declare a standard fallback value directly before the property containing the if() expression. Browser engines that do not recognize if() will treat the second line as invalid and retain the fallback value due to standard CSS cascading rules, preventing broken component rendering.