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CSS

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HTML 

              
                <script>
document.documentElement.dataset.embed = window.location.search.includes('type=embed') ? "yep" : "nope";
</script>

<main>
	<h1>Styling <code>&lt;details&gt;</code>: Horizontal Accordion <em>(no animation)</em></h1>

	<h2>Demo</h2>
	
	<div id="demo">
		<div class="accordion-wrapper">
			<details name="accordion" id="boating" open>
			<summary>
				<span>🚤</span>
				<img draggable=false src="https://raw.githubusercontent.com/kevin-powell/accordion/8551c559e3e8d9a9cca7a983c9e8903ef533f189/public/assets/boat.webp" alt="">
			</summary>
			<div class="details-content-wrapper">
				<h3>Boating</h3>
				<p>Port mutiny draught handsomely ye furl flogging line shrouds hulk. Spirits Plate Fleet code of conduct.</p>
			</div>
		</details>
		<details name="accordion" id="anchoring">
			<summary>
				<span>⚓️</span>
				<img draggable=false src="https://raw.githubusercontent.com/kevin-powell/accordion/8551c559e3e8d9a9cca7a983c9e8903ef533f189/public/assets/anchor.webp" alt="">
			</summary>
			<div class="details-content-wrapper">
				<h3>Anchoring</h3>
				<p>Ahoy league hands Sea Legs keelhaul salmagundi fire ship crimp Privateer galleon. Booty boom yard boatswain quarter.</p>
			</div>
		</details>
		<details name="accordion" id="fishing">
			<summary>
				<span>🎣</span>
				<img draggable=false src="https://raw.githubusercontent.com/kevin-powell/accordion/8551c559e3e8d9a9cca7a983c9e8903ef533f189/public/assets/fishing.webp" alt="">
			</summary>
			<div class="details-content-wrapper">
				<h3>Fishing</h3>
				<p>No prey, no pay heave down splice the main brace furl cable snow walk the plank chase guns piracy bucko.</p>
			</div>
		</details>
		<details name="accordion" id="lighthouses">
			<summary>
				<span>🔦</span>
				<img draggable=false src="https://raw.githubusercontent.com/kevin-powell/accordion/8551c559e3e8d9a9cca7a983c9e8903ef533f189/public/assets/lighthouse.webp" alt="">
			</summary>
			<div class="details-content-wrapper">
				<h3>Lighthouses</h3>
				<p>Deadlights squiffy salmagundi cable pinnace parrel topsail Corsair Arr mizzenmast.</p>
			</div>
		</details>
		<details name="accordion" id="reefs">
			<summary>
				<span>🪸</span>
				<img draggable=false src="https://raw.githubusercontent.com/kevin-powell/accordion/8551c559e3e8d9a9cca7a983c9e8903ef533f189/public/assets/reef.webp" alt="">
			</summary>
			<div class="details-content-wrapper">
				<h3>Reefs</h3>
				<p>Keel yard poop deck brigantine gaff six pounders bring a spring
					upon her cable interloper lad pink.</p>
			</div>
		</details>
		</div>
	</div>

	<p>Demo for <a href="https://developer.chrome.com/blog/styling-details" target="_top">https://developer.chrome.com/blog/styling-details</a>, built after <a href="https://codepen.io/jakob-e/full/MWzRjNe" target="_top">https://codepen.io/jakob-e/full/MWzRjNe</a></p>

	<h2>The Code</h2>
	
	<h3>UI</h3>
	
	<pre><code>.accordion-wrapper {
	display: flex;
	flex-direction: row;
	gap: 1rem;
}

details {
	display: flex;
	flex-direction: row;
	
	height: 30rem;
	border-radius: 2rem;
	overflow: hidden;
	
	/* To make the image positioning work …*/
	position: relative;
	z-index: 1;
	
	/* Hide marker */
	::marker {
		content: '';
	}
	
	/* The image is tucked in the summary, because otherwise it would be hidden when not [open] as it ends up in the ::details-content pseudo */
	summary img {
		position: absolute;
		top: 0;
		left: 0;
		width: 100%;
		height: 100%;
		object-fit: cover;
		z-index: -1;
		transition: filter 0.5s ease;
	}
	/* Animate the image */
	&[open] summary img {
		filter: brightness(0.5);
	}
	
	summary {
		padding: 1rem 1em;
		width: 5rem;
		flex-shrink: 0; /* Prevent shrinking */
		text-align: center;
	}
	
	.details-content-wrapper {
		padding: 1.5rem 1em;
		width: 300px; /* Fixate the width of the content so that the text doesn’t wrap/unwrap when expanding the details */
	}
}

.details-content-wrapper {
	/* Animate-in the text when open */
	p {
		transform: translateY(2rem);
		opacity: 0;
		transition: all 0.5s ease;
		transition-delay: 0.5s;
	}
	
	[open] & p {
		transform: none;
		opacity: 1;
		transition-delay: 0.5s;
	}
}</code></pre>
</main>
!

CSS 

              
                @supports selector(::details-content) {
	.warning {
		display: none;
	}
}

.accordion-wrapper {
	display: flex;
	flex-direction: row;
	gap: 1rem;
	width: min-content;
	margin: 0 auto;
}

details {
	display: flex;
	flex-direction: row;

	background: transparent;
	color: white;
	
	height: 30rem;
	border-radius: 2rem;
	overflow: hidden;
	
	/* To make the image work …*/
	position: relative;
	z-index: 1;
	
	/* Hide marker */
	::marker {
		content: '';
	}
	
	/* The image is tucked in the summary, because otherwise it would be hidden when not [open] as it ends up in the ::details-content pseudo */
	summary img {
		position: absolute;
		top: 0;
		left: 0;
		width: 100%;
		height: 100%;
		object-fit: cover;
		z-index: -1;
		transition: filter 0.5s ease;
	}
	/* Animate the image */
	&[open] summary img {
		filter: brightness(0.5);
	}
	
	summary {
		padding: 1rem 1em;
		width: 5rem;
		flex-shrink: 0; /* Prevent shrinking */
		text-align: center;
		
		span {
			display: grid;
			place-content: center;
			width: 100%;
			aspect-ratio: 1;
			border-radius: 50%;
			background: rgb(0 0 0 / 0.25);
		}
		
		&:focus {
			outline: none;
		}
	}
	
	.details-content-wrapper {
		padding: 1.5rem 1em;
		width: 300px;
	}
	
	&:hover, &:has(summary:focus) {
		outline: 3px solid cadetblue;
		outline-offset: 3px;
	}
}

.details-content-wrapper {
	/* We need margin-trim … */
	:first-child { margin-top: 0; }
	:last-child {	margin-bottom: 0;	}
	
	/* Animate-in the text when open */
	p {
		transform: translateY(2rem);
		opacity: 0;
		transition: all 0.5s ease;
		transition-delay: 0.5s;
	}
	
	[open] & p {
		transform: none;
		opacity: 1;
		transition-delay: 0.5s;
	}
}

@layer reset {
	* {
		margin: 0;
		padding: 0;
		box-sizing: border-box;
	}

	html,
	body {
		height: 100%;
	}
	
	html {
		font-size: 14px;
	}
}

@layer baselayout {
	html {
		color: #444;
		font-family: system-ui;
		line-height: 1.42;
		
		overscroll-behavior-x: none;
		overflow: auto;
	}

	main {
		max-width: 90ch;
		margin: 0 auto;
		padding-bottom: 10rem;
	}

	p {
		margin-bottom: 1em;
	}
	
	h1, h2 {
		margin: 4em 0 1em;
	}
	h3 {
		margin: 1em 0 0.5em;
	}
	
	#demo {
		padding: 1em;
		border: 1px solid #ccc;
		background: #f4f6f9;
	}
}

@layer code {
	pre {
		border: 1px solid #dedede;
		padding: 1em;
		background: #f7f7f7;
		font-family: "Courier 10 Pitch", Courier, monospace;
		overflow-x: auto;
		border-left: 0.4em solid cornflowerblue;
		tab-size: 4;
	}

	code:not(pre code) {
		background: #f7f7f7;
		border: 1px solid rgb(0 0 0 / 0.2);
		padding: 0.1rem 0.3rem;
		margin: 0.1rem 0;
		border-radius: 0.2rem;
		/* 			display: inline-block; */
		-webkit-box-decoration-break: clone;
		white-space: pre-wrap;
	}
}

@layer warning {
	.warning {
		box-sizing: border-box;
		padding: 1em;
		margin: 1em 0;
		border: 1px solid #ccc;
		background: rgba(255 255 205 / 0.8);
	}

	.warning > :first-child {
		margin-top: 0;
	}

	.warning > :last-child {
		margin-bottom: 0;
	}

	.warning a {
		color: blue;
	}
	.warning--info {
		border: 1px solid #123456;
		background: rgb(205 230 255 / 0.8);
	}
	.warning--alarm {
		border: 1px solid red;
		background: #ff000010;
	}
}

/* Hide a bunch of stuff when embedded */
:root[data-embed="yep"] {
	main {
		padding: 2em 1em;
		
		:not(p.warning, p.warning *, #demo, #demo *, #demo ~ p, #demo ~ p *) {
			display: none;
		}
	}
	#demo ~ p {
		margin-top: 1em;
		text-align: center;
	}
}
!

JS
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