32 Tailwind CSS Accordions — Vertical & Horizontal
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All 32 in 32 Tailwind CSS Accordions — Vertical & Horizontal

  1. 01Tailwind CSS FAQ Accordion with Details and Summary
  2. 02Tailwind CSS Mobile Navigation Accordion Menu
  3. 03Tailwind CSS Product Filter Sidebar Accordion
  4. 04Tailwind CSS Nested Accordion Tree View
  5. 05Smooth Animated Tailwind Accordion with Height Transition
  6. 06Tailwind CSS Exclusive Accordion — Only One Open at a Time
  7. 07Minimal Tailwind Accordion with Animated Underline
  8. 08Tailwind CSS Numbered Steps Accordion for Onboarding
  9. 09Tailwind Accordion with Plus Minus Icon Animation
  10. 10Tailwind CSS Accordion Card with Rotating Chevron
  11. 11Brutalist Tailwind CSS Accordion
  12. 12Glassmorphism Tailwind CSS Accordion
  13. 13Tailwind CSS Timeline Accordion for Changelogs
  14. 14Tailwind CSS Card Accordion with Elevation on Open
  15. 15Skewed Tailwind CSS Accordion with Slanted Headers
  16. 16Tailwind CSS Stepped Cascade Accordion
  17. 17Tailwind Accordion with Circular Progress Ring
  18. 18Tailwind CSS Accordion with Marquee Scrolling Title
  19. 19Tailwind CSS Code Editor Accordion for Documentation
  20. 20Tailwind CSS 3D Paper Fold Accordion
  21. 21Tailwind CSS Playlist Accordion with Equalizer Animation
  22. 22Tailwind CSS Stacked Cards Accordion
  23. 23Tailwind Accordion with Animated Gradient Border
  24. 24Dark Tailwind CSS Accordion with Aurora Glow
  25. 25Tailwind CSS Horizontal Accordion Tabs
  26. 26Tailwind CSS Expanding Image Gallery Accordion
  27. 27Tailwind CSS Horizontal Accordion Feature Section
  28. 28Editorial Horizontal Accordion with Numbered Spines in Tailwind
  29. 29Tailwind CSS Horizontal Accordion with clip-path Reveal
  30. 30Tailwind CSS Album Shelf Horizontal Accordion
  31. 31Tailwind CSS Cinematic Horizontal Accordion Slider
  32. 32Tailwind CSS Aurora Gradient Horizontal Accordion
Tailwind v4MIT licensed

Tailwind Accordion with Circular Progress Ring

A course-syllabus accordion where every module header wears a conic-gradient progress ring. Each ring shows its module's completion at rest; opening the module sweeps a bright arc around to that value, animated by a registered @property angle and driven entirely by group-open:[--tac17-arc:var(--tac17-to)]. The panel underneath grows with ::details-content + interpolate-size, and it is all native <details> with no JavaScript.

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The code

<section class="tac-17 w-full min-h-svh grid place-items-center bg-tac17-bg bg-[radial-gradient(80%_55%_at_50%_-5%,var(--color-tac17-glow),transparent_70%)] px-5 py-14 font-tac17-sans text-tac17-ink [interpolate-size:allow-keywords]" aria-label="Circular progress ring accordion demo">
  <div class="grid w-full justify-items-center gap-7">
    <div class="w-full max-w-[600px] rounded-3xl bg-tac17-card/80 p-[clamp(20px,4vw,32px)] shadow-[0_1px_0_oklch(1_0_0/0.06)_inset,0_30px_80px_-30px_oklch(0_0_0/0.75)] ring-1 ring-white/10">
      <header class="mb-6">
        <p class="text-xs font-semibold tracking-[0.16em] uppercase text-tac17-acc">Course · Frontend Foundations</p>
        <h2 class="mt-2 text-[clamp(22px,3.4vw,27px)] font-bold tracking-[-0.02em] text-balance">Modern CSS Layout Systems</h2>
        <div class="mt-4 flex items-center gap-3">
          <div class="h-1.5 flex-1 overflow-hidden rounded-full bg-tac17-track" aria-hidden="true"><div class="h-full w-[47%] rounded-full bg-linear-to-r from-tac17-acc2 to-tac17-acc shadow-[0_0_12px_var(--color-tac17-acc)]"></div></div>
          <p class="font-tac17-mono text-xs text-tac17-mut"><span class="text-tac17-ink">47%</span> · 9 of 19 lessons</p>
        </div>
      </header>

      <div class="divide-y divide-white/8 border-y border-white/8">
        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:360deg">
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full [background:conic-gradient(color-mix(in_oklab,var(--color-tac17-ok)_38%,transparent)_var(--tac17-to),var(--color-tac17-track)_0)] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="absolute inset-0 rounded-full [--tac17-arc:0deg] [background:conic-gradient(var(--color-tac17-ok)_calc(var(--tac17-arc)-0.5deg),transparent_var(--tac17-arc))] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))] drop-shadow-[0_0_6px_var(--color-tac17-ok)] transition-[--tac17-arc] duration-[1100ms] ease-[cubic-bezier(.3,.7,.2,1)] group-open:[--tac17-arc:var(--tac17-to)] motion-reduce:transition-none"></span>
              <svg class="relative size-4 text-tac17-ok" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"/></svg>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em]">Module 1 · Flexbox, properly</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">5 lessons · 52 min</span>
            </span>
            <span class="rounded-full bg-tac17-ok/12 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-ok ring-1 ring-tac17-ok/25 max-sm:hidden">Complete</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <ol class="grid gap-1 text-sm">
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-ok/15 text-tac17-ok" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">The two axes, finally explained</span><span class="font-tac17-mono text-xs text-tac17-mut">9:40</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-ok/15 text-tac17-ok" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">flex-basis vs width</span><span class="font-tac17-mono text-xs text-tac17-mut">11:05</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-ok/15 text-tac17-ok" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">Gap, wrap and the min-width trap</span><span class="font-tac17-mono text-xs text-tac17-mut">13:20</span></li>
            </ol>
            <p class="mt-3 text-[13px] text-tac17-mut">Certificate badge earned on May 14 · <span class="text-tac17-ok">quiz 9/10</span></p>
          </div>
        </details>

        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:223deg" open>
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full [background:conic-gradient(color-mix(in_oklab,var(--color-tac17-acc)_38%,transparent)_var(--tac17-to),var(--color-tac17-track)_0)] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="absolute inset-0 rounded-full [--tac17-arc:0deg] [background:conic-gradient(var(--color-tac17-acc)_calc(var(--tac17-arc)-0.5deg),transparent_var(--tac17-arc))] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))] drop-shadow-[0_0_6px_var(--color-tac17-acc)] transition-[--tac17-arc] duration-[1100ms] ease-[cubic-bezier(.3,.7,.2,1)] group-open:[--tac17-arc:var(--tac17-to)] motion-reduce:transition-none"></span>
              <span class="relative font-tac17-mono text-[11px] font-semibold text-tac17-ink">62<span class="text-tac17-mut">%</span></span>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em] group-open:text-tac17-acc">Module 2 · Grid &amp; subgrid</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">6 lessons · 1h 04m</span>
            </span>
            <span class="rounded-full bg-tac17-acc/12 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-acc ring-1 ring-tac17-acc/25 max-sm:hidden">In progress</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <ol class="grid gap-1 text-sm">
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-acc/15 text-tac17-acc" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">Tracks, lines and areas</span><span class="font-tac17-mono text-xs text-tac17-mut">12:10</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-acc/15 text-tac17-acc" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">minmax(), auto-fit and auto-fill</span><span class="font-tac17-mono text-xs text-tac17-mut">10:45</span></li>
              <li class="flex items-center gap-3 rounded-lg bg-white/[0.04] px-2 py-1.5 -mx-2 ring-1 ring-tac17-acc/20"><span class="grid size-5 flex-none place-items-center rounded-full ring-2 ring-tac17-acc" aria-hidden="true"><span class="size-1.5 rounded-full bg-tac17-acc"></span></span><span class="flex-1 font-medium text-tac17-ink">Subgrid in practice: aligned card footers</span><span class="font-tac17-mono text-xs text-tac17-acc">4:12 left</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Masonry-style layouts without JS</span><span class="font-tac17-mono text-xs text-tac17-mut">14:30</span></li>
            </ol>
            <button type="button" class="mt-4 inline-flex min-h-11 items-center gap-2 rounded-xl bg-tac17-acc px-4 text-sm font-semibold text-tac17-bg shadow-[0_8px_24px_-8px_var(--color-tac17-acc)] transition hover:brightness-110 active:scale-[0.98] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc">
              <svg class="size-4" viewBox="0 0 16 16" aria-hidden="true"><path d="M5 3.5v9l7.5-4.5z" fill="currentColor"/></svg>Resume lesson 3
            </button>
          </div>
        </details>

        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:90deg">
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full [background:conic-gradient(color-mix(in_oklab,var(--color-tac17-acc)_38%,transparent)_var(--tac17-to),var(--color-tac17-track)_0)] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="absolute inset-0 rounded-full [--tac17-arc:0deg] [background:conic-gradient(var(--color-tac17-acc)_calc(var(--tac17-arc)-0.5deg),transparent_var(--tac17-arc))] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))] drop-shadow-[0_0_6px_var(--color-tac17-acc)] transition-[--tac17-arc] duration-[1100ms] ease-[cubic-bezier(.3,.7,.2,1)] group-open:[--tac17-arc:var(--tac17-to)] motion-reduce:transition-none"></span>
              <span class="relative font-tac17-mono text-[11px] font-semibold text-tac17-ink">25<span class="text-tac17-mut">%</span></span>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em] group-open:text-tac17-acc">Module 3 · Container queries</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">4 lessons · 46 min</span>
            </span>
            <span class="rounded-full bg-tac17-acc/12 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-acc ring-1 ring-tac17-acc/25 max-sm:hidden">Started</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <ol class="grid gap-1 text-sm">
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-acc/15 text-tac17-acc" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">Size queries vs media queries</span><span class="font-tac17-mono text-xs text-tac17-mut">10:15</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Container units: cqi and cqb</span><span class="font-tac17-mono text-xs text-tac17-mut">11:40</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Style queries for theming</span><span class="font-tac17-mono text-xs text-tac17-mut">12:05</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Project: a responsive pricing card</span><span class="font-tac17-mono text-xs text-tac17-mut">12:00</span></li>
            </ol>
          </div>
        </details>

        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:0deg">
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full bg-tac17-track [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="relative font-tac17-mono text-[11px] font-semibold text-tac17-mut">0%</span>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em] group-open:text-tac17-acc">Module 4 · Anchor positioning</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">4 lessons · 58 min</span>
            </span>
            <span class="rounded-full bg-white/6 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-mut ring-1 ring-white/12 max-sm:hidden">Up next</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <p class="text-sm leading-relaxed text-tac17-soft text-pretty">Tooltips, popovers and menus that stay attached to their trigger, with zero JavaScript positioning. Unlocks after the Module 3 project.</p>
          </div>
        </details>
      </div>
    </div>
    <p aria-hidden="true" class="rounded-full px-3.5 py-2 font-tac17-mono text-[11.5px] text-tac17-mut ring-1 ring-white/10">@property &lt;angle&gt; · group-open:[--tac17-arc:…] · conic-gradient + mask</p>
  </div>
</section>
@import "tailwindcss";

@theme {
  --color-tac17-bg: #070b14;
  --color-tac17-bg: oklch(0.15 0.02 260);
  --color-tac17-glow: #0f3a4a99;
  --color-tac17-glow: oklch(0.33 0.07 220 / 0.6);
  --color-tac17-card: #111827;
  --color-tac17-card: oklch(0.21 0.025 262);
  --color-tac17-track: #263044;
  --color-tac17-track: oklch(0.31 0.03 262);
  --color-tac17-ink: #eef3f9;
  --color-tac17-ink: oklch(0.96 0.01 250);
  --color-tac17-soft: #c5cedb;
  --color-tac17-soft: oklch(0.85 0.02 255);
  --color-tac17-mut: #98a3b6;
  --color-tac17-mut: oklch(0.72 0.025 260);
  --color-tac17-acc: #3fd6f0;
  --color-tac17-acc: oklch(0.81 0.13 215);
  --color-tac17-acc2: #5b7cfa;
  --color-tac17-acc2: oklch(0.63 0.18 268);
  --color-tac17-ok: #4ade9a;
  --color-tac17-ok: oklch(0.82 0.16 158);
  --font-tac17-sans: 'Sora', system-ui, sans-serif;
  --font-tac17-mono: 'Geist Mono', ui-monospace, monospace;
}
/* Root rule: the full-bleed contract, stated in CSS as well as in the markup's utilities, so the
   stage is sized before the browser build compiles. */

.tac-17 {
  width: 100%;
  min-height: 100svh;
}
/* Registered so the arc interpolates: an untyped custom property can only snap from 0 to its target. */

@property --tac17-arc {
  syntax: '<angle>';
  initial-value: 0deg;
  inherits: false;
}

Setup — do this once per project

Skip this if your project already runs Tailwind v4.

1Load Tailwind
<script src="https://cdn.jsdelivr.net/npm/@tailwindcss/browser@4"></script>

Compiles in the browser — perfect for a CodePen or a quick test, not for production.

2Add the stylesheetRequiredthe @theme block is what makes the custom utilities exist
@import "tailwindcss";

@theme {
  --color-tac17-bg: #070b14;
  --color-tac17-bg: oklch(0.15 0.02 260);
  --color-tac17-glow: #0f3a4a99;
  --color-tac17-glow: oklch(0.33 0.07 220 / 0.6);
  --color-tac17-card: #111827;
  --color-tac17-card: oklch(0.21 0.025 262);
  --color-tac17-track: #263044;
  --color-tac17-track: oklch(0.31 0.03 262);
  --color-tac17-ink: #eef3f9;
  --color-tac17-ink: oklch(0.96 0.01 250);
  --color-tac17-soft: #c5cedb;
  --color-tac17-soft: oklch(0.85 0.02 255);
  --color-tac17-mut: #98a3b6;
  --color-tac17-mut: oklch(0.72 0.025 260);
  --color-tac17-acc: #3fd6f0;
  --color-tac17-acc: oklch(0.81 0.13 215);
  --color-tac17-acc2: #5b7cfa;
  --color-tac17-acc2: oklch(0.63 0.18 268);
  --color-tac17-ok: #4ade9a;
  --color-tac17-ok: oklch(0.82 0.16 158);
  --font-tac17-sans: 'Sora', system-ui, sans-serif;
  --font-tac17-mono: 'Geist Mono', ui-monospace, monospace;
}
/* Root rule: the full-bleed contract, stated in CSS as well as in the markup's utilities, so the
   stage is sized before the browser build compiles. */

.tac-17 {
  width: 100%;
  min-height: 100svh;
}
/* Registered so the arc interpolates: an untyped custom property can only snap from 0 to its target. */

@property --tac17-arc {
  syntax: '<angle>';
  initial-value: 0deg;
  inherits: false;
}
3Fonts used by this demooptional — skip if you have your own type stack
<link rel="preconnect" href="https://fonts.googleapis.com">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Sora:wght@400..800&family=Geist+Mono:wght@400..600&display=swap">

What changed in the port

Which parts became utilities, which stayed CSS, and why.

  • The original's .item[open] .dial{--arc:360deg} became group-open:[--tac17-arc:var(--tac17-to)] on the ring itself; the transition is transition-[--tac17-arc], so the state change and its animation sit in one class list.
  • @property --tac17-arc stayed in CSS: an at-rule has no utility spelling, and without it the angle cannot be interpolated.
  • UI upgrade from the CSS original: rings now carry real data. Each module's completion (--tac17-to) shows at rest as a dim arc, and opening sweeps a glowing arc to that value instead of always to 360°. A course-level progress bar, status badges and a lesson list with a highlighted current lesson and a Resume button turn the demo into a real LMS syllabus.
  • UI upgrade: the ring is cut out with a radial mask instead of an inner disc painted in the row's background, so it no longer breaks on hover tints. Panels animate their height through [&::details-content] utilities, and muted copy is raised to 6:1 on the dark card.
Paste this into ChatGPT, Claude, Cursor, or any coding assistant. The block below is pre-framed with everything the AI needs to integrate this demo into your project — markup, styles, scoping notes, and the source URL. Hit Copy and paste straight into your chat.
Here's a working CSS demo from CodeFronts. Use it as-is or adapt to your framework. All classes are scoped under a unique prefix so the code won't collide with your existing styles. MIT licensed.
Demo: Tailwind Accordion with Circular Progress Ring
Source: https://codefronts.com/navigation/tailwind-css-accordions/tailwind-accordion-circular-progress-ring/

A course-syllabus accordion where every module header wears a conic-gradient progress ring. Each ring shows its module's completion at rest; opening the module sweeps a bright arc around to that value, animated by a registered @property angle and driven entirely by group-open:[--tac17-arc:var(--tac17-to)]. The panel underneath grows with ::details-content + interpolate-size, and it is all native <details> with no JavaScript.
## HTML
```html
<section class="tac-17 w-full min-h-svh grid place-items-center bg-tac17-bg bg-[radial-gradient(80%_55%_at_50%_-5%,var(--color-tac17-glow),transparent_70%)] px-5 py-14 font-tac17-sans text-tac17-ink [interpolate-size:allow-keywords]" aria-label="Circular progress ring accordion demo">
  <div class="grid w-full justify-items-center gap-7">
    <div class="w-full max-w-[600px] rounded-3xl bg-tac17-card/80 p-[clamp(20px,4vw,32px)] shadow-[0_1px_0_oklch(1_0_0/0.06)_inset,0_30px_80px_-30px_oklch(0_0_0/0.75)] ring-1 ring-white/10">
      <header class="mb-6">
        <p class="text-xs font-semibold tracking-[0.16em] uppercase text-tac17-acc">Course · Frontend Foundations</p>
        <h2 class="mt-2 text-[clamp(22px,3.4vw,27px)] font-bold tracking-[-0.02em] text-balance">Modern CSS Layout Systems</h2>
        <div class="mt-4 flex items-center gap-3">
          <div class="h-1.5 flex-1 overflow-hidden rounded-full bg-tac17-track" aria-hidden="true"><div class="h-full w-[47%] rounded-full bg-linear-to-r from-tac17-acc2 to-tac17-acc shadow-[0_0_12px_var(--color-tac17-acc)]"></div></div>
          <p class="font-tac17-mono text-xs text-tac17-mut"><span class="text-tac17-ink">47%</span> · 9 of 19 lessons</p>
        </div>
      </header>

      <div class="divide-y divide-white/8 border-y border-white/8">
        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:360deg">
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full [background:conic-gradient(color-mix(in_oklab,var(--color-tac17-ok)_38%,transparent)_var(--tac17-to),var(--color-tac17-track)_0)] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="absolute inset-0 rounded-full [--tac17-arc:0deg] [background:conic-gradient(var(--color-tac17-ok)_calc(var(--tac17-arc)-0.5deg),transparent_var(--tac17-arc))] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))] drop-shadow-[0_0_6px_var(--color-tac17-ok)] transition-[--tac17-arc] duration-[1100ms] ease-[cubic-bezier(.3,.7,.2,1)] group-open:[--tac17-arc:var(--tac17-to)] motion-reduce:transition-none"></span>
              <svg class="relative size-4 text-tac17-ok" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"/></svg>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em]">Module 1 · Flexbox, properly</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">5 lessons · 52 min</span>
            </span>
            <span class="rounded-full bg-tac17-ok/12 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-ok ring-1 ring-tac17-ok/25 max-sm:hidden">Complete</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <ol class="grid gap-1 text-sm">
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-ok/15 text-tac17-ok" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">The two axes, finally explained</span><span class="font-tac17-mono text-xs text-tac17-mut">9:40</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-ok/15 text-tac17-ok" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">flex-basis vs width</span><span class="font-tac17-mono text-xs text-tac17-mut">11:05</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-ok/15 text-tac17-ok" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">Gap, wrap and the min-width trap</span><span class="font-tac17-mono text-xs text-tac17-mut">13:20</span></li>
            </ol>
            <p class="mt-3 text-[13px] text-tac17-mut">Certificate badge earned on May 14 · <span class="text-tac17-ok">quiz 9/10</span></p>
          </div>
        </details>

        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:223deg" open>
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full [background:conic-gradient(color-mix(in_oklab,var(--color-tac17-acc)_38%,transparent)_var(--tac17-to),var(--color-tac17-track)_0)] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="absolute inset-0 rounded-full [--tac17-arc:0deg] [background:conic-gradient(var(--color-tac17-acc)_calc(var(--tac17-arc)-0.5deg),transparent_var(--tac17-arc))] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))] drop-shadow-[0_0_6px_var(--color-tac17-acc)] transition-[--tac17-arc] duration-[1100ms] ease-[cubic-bezier(.3,.7,.2,1)] group-open:[--tac17-arc:var(--tac17-to)] motion-reduce:transition-none"></span>
              <span class="relative font-tac17-mono text-[11px] font-semibold text-tac17-ink">62<span class="text-tac17-mut">%</span></span>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em] group-open:text-tac17-acc">Module 2 · Grid &amp; subgrid</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">6 lessons · 1h 04m</span>
            </span>
            <span class="rounded-full bg-tac17-acc/12 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-acc ring-1 ring-tac17-acc/25 max-sm:hidden">In progress</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <ol class="grid gap-1 text-sm">
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-acc/15 text-tac17-acc" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">Tracks, lines and areas</span><span class="font-tac17-mono text-xs text-tac17-mut">12:10</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-acc/15 text-tac17-acc" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">minmax(), auto-fit and auto-fill</span><span class="font-tac17-mono text-xs text-tac17-mut">10:45</span></li>
              <li class="flex items-center gap-3 rounded-lg bg-white/[0.04] px-2 py-1.5 -mx-2 ring-1 ring-tac17-acc/20"><span class="grid size-5 flex-none place-items-center rounded-full ring-2 ring-tac17-acc" aria-hidden="true"><span class="size-1.5 rounded-full bg-tac17-acc"></span></span><span class="flex-1 font-medium text-tac17-ink">Subgrid in practice: aligned card footers</span><span class="font-tac17-mono text-xs text-tac17-acc">4:12 left</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Masonry-style layouts without JS</span><span class="font-tac17-mono text-xs text-tac17-mut">14:30</span></li>
            </ol>
            <button type="button" class="mt-4 inline-flex min-h-11 items-center gap-2 rounded-xl bg-tac17-acc px-4 text-sm font-semibold text-tac17-bg shadow-[0_8px_24px_-8px_var(--color-tac17-acc)] transition hover:brightness-110 active:scale-[0.98] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc">
              <svg class="size-4" viewBox="0 0 16 16" aria-hidden="true"><path d="M5 3.5v9l7.5-4.5z" fill="currentColor"/></svg>Resume lesson 3
            </button>
          </div>
        </details>

        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:90deg">
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full [background:conic-gradient(color-mix(in_oklab,var(--color-tac17-acc)_38%,transparent)_var(--tac17-to),var(--color-tac17-track)_0)] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="absolute inset-0 rounded-full [--tac17-arc:0deg] [background:conic-gradient(var(--color-tac17-acc)_calc(var(--tac17-arc)-0.5deg),transparent_var(--tac17-arc))] [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))] drop-shadow-[0_0_6px_var(--color-tac17-acc)] transition-[--tac17-arc] duration-[1100ms] ease-[cubic-bezier(.3,.7,.2,1)] group-open:[--tac17-arc:var(--tac17-to)] motion-reduce:transition-none"></span>
              <span class="relative font-tac17-mono text-[11px] font-semibold text-tac17-ink">25<span class="text-tac17-mut">%</span></span>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em] group-open:text-tac17-acc">Module 3 · Container queries</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">4 lessons · 46 min</span>
            </span>
            <span class="rounded-full bg-tac17-acc/12 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-acc ring-1 ring-tac17-acc/25 max-sm:hidden">Started</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <ol class="grid gap-1 text-sm">
              <li class="flex items-center gap-3 py-1.5"><span class="grid size-5 flex-none place-items-center rounded-full bg-tac17-acc/15 text-tac17-acc" aria-hidden="true"><svg class="size-3" viewBox="0 0 16 16"><path d="M3.5 8.4 6.6 11.4 12.5 5" fill="none" stroke="currentColor" stroke-width="2.4" stroke-linecap="round"/></svg></span><span class="flex-1 text-tac17-soft">Size queries vs media queries</span><span class="font-tac17-mono text-xs text-tac17-mut">10:15</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Container units: cqi and cqb</span><span class="font-tac17-mono text-xs text-tac17-mut">11:40</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Style queries for theming</span><span class="font-tac17-mono text-xs text-tac17-mut">12:05</span></li>
              <li class="flex items-center gap-3 py-1.5"><span class="size-5 flex-none rounded-full ring-1 ring-inset ring-white/20" aria-hidden="true"></span><span class="flex-1 text-tac17-soft">Project: a responsive pricing card</span><span class="font-tac17-mono text-xs text-tac17-mut">12:00</span></li>
            </ol>
          </div>
        </details>

        <details class="group [&::details-content]:h-0 [&::details-content]:overflow-clip [&::details-content]:transition-[height,content-visibility] [&::details-content]:duration-500 [&::details-content]:ease-[cubic-bezier(.2,.7,.2,1)] [&::details-content]:[transition-behavior:allow-discrete] open:[&::details-content]:h-auto motion-reduce:[&::details-content]:transition-none" style="--tac17-to:0deg">
          <summary class="flex min-h-11 cursor-pointer list-none items-center gap-4 rounded-xl px-2 py-3.5 transition-colors hover:bg-white/[0.035] focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-tac17-acc [&::-webkit-details-marker]:hidden">
            <span class="relative grid size-12 flex-none place-items-center" aria-hidden="true">
              <span class="absolute inset-0 rounded-full bg-tac17-track [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]"></span>
              <span class="relative font-tac17-mono text-[11px] font-semibold text-tac17-mut">0%</span>
            </span>
            <span class="min-w-0 flex-1">
              <span class="block text-[15.5px] font-semibold tracking-[-0.01em] group-open:text-tac17-acc">Module 4 · Anchor positioning</span>
              <span class="mt-1 block font-tac17-mono text-xs text-tac17-mut">4 lessons · 58 min</span>
            </span>
            <span class="rounded-full bg-white/6 px-2.5 py-1 text-[11.5px] font-semibold text-tac17-mut ring-1 ring-white/12 max-sm:hidden">Up next</span>
            <svg class="size-4 flex-none text-tac17-mut transition-transform duration-300 group-open:rotate-180 group-open:text-tac17-ink motion-reduce:transition-none" viewBox="0 0 16 16" aria-hidden="true"><path d="M4 6.2 8 10l4-3.8" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"/></svg>
          </summary>
          <div class="pb-5 pl-[4.5rem] pr-2 max-sm:pl-2">
            <p class="text-sm leading-relaxed text-tac17-soft text-pretty">Tooltips, popovers and menus that stay attached to their trigger, with zero JavaScript positioning. Unlocks after the Module 3 project.</p>
          </div>
        </details>
      </div>
    </div>
    <p aria-hidden="true" class="rounded-full px-3.5 py-2 font-tac17-mono text-[11.5px] text-tac17-mut ring-1 ring-white/10">@property &lt;angle&gt; · group-open:[--tac17-arc:…] · conic-gradient + mask</p>
  </div>
</section>
```
## CSS
```css
@import "tailwindcss";

@theme {
  --color-tac17-bg: #070b14;
  --color-tac17-bg: oklch(0.15 0.02 260);
  --color-tac17-glow: #0f3a4a99;
  --color-tac17-glow: oklch(0.33 0.07 220 / 0.6);
  --color-tac17-card: #111827;
  --color-tac17-card: oklch(0.21 0.025 262);
  --color-tac17-track: #263044;
  --color-tac17-track: oklch(0.31 0.03 262);
  --color-tac17-ink: #eef3f9;
  --color-tac17-ink: oklch(0.96 0.01 250);
  --color-tac17-soft: #c5cedb;
  --color-tac17-soft: oklch(0.85 0.02 255);
  --color-tac17-mut: #98a3b6;
  --color-tac17-mut: oklch(0.72 0.025 260);
  --color-tac17-acc: #3fd6f0;
  --color-tac17-acc: oklch(0.81 0.13 215);
  --color-tac17-acc2: #5b7cfa;
  --color-tac17-acc2: oklch(0.63 0.18 268);
  --color-tac17-ok: #4ade9a;
  --color-tac17-ok: oklch(0.82 0.16 158);
  --font-tac17-sans: 'Sora', system-ui, sans-serif;
  --font-tac17-mono: 'Geist Mono', ui-monospace, monospace;
}
/* Root rule: the full-bleed contract, stated in CSS as well as in the markup's utilities, so the
   stage is sized before the browser build compiles. */

.tac-17 {
  width: 100%;
  min-height: 100svh;
}
/* Registered so the arc interpolates: an untyped custom property can only snap from 0 to its target. */

@property --tac17-arc {
  syntax: '<angle>';
  initial-value: 0deg;
  inherits: false;
}
```

How this works

Two rings stacked, one of them animated. The lower layer is static: the module's progress at 35% strength over a slate track, so you can scan completion with everything closed. The upper layer is the sweep. Its arc is the registered angle --tac17-arc, at 0deg while closed:

<span class="[--tac17-arc:0deg] group-open:[--tac17-arc:var(--tac17-to)]
  transition-[--tac17-arc] duration-[1100ms]
  [background:conic-gradient(var(--color-tac17-acc)_var(--tac17-arc),transparent_0)]
  [mask:radial-gradient(farthest-side,transparent_calc(100%-4px),#000_calc(100%-3.5px))]">

Why @property stays in CSS. An unregistered custom property is just a string, so the browser can only swap it and the ring would snap from empty to full. Registering it with syntax: '<angle>' lets transition-[--tac17-arc] interpolate it frame by frame. The mask punches the centre out, so the ring sits on any background without the original's colour-matched inner disc.

Make it yours

  • Set each module's progress with style="--tac17-to:…deg" on the <details>: 360deg is complete, 0deg not started (3.6deg per percent).
  • Ring thickness: change both 4px / 3.5px stops in the mask; keep them half a pixel apart so the inner edge anti-aliases.
  • Sweep speed: duration-[1100ms] on the sweep layer. The ease-[cubic-bezier(.3,.7,.2,1)] curve makes it decelerate like a dial settling.
  • Single-open syllabus: add name="tac17-mod" to every <details>.

Gotchas — read before shipping

  • Without the @property registration the ring still fills on open, but instantly. Firefox before 128 and other older engines get that snap, which is an acceptable fallback.
  • transition-[--tac17-arc] must sit on the element that owns the property. inherits: false keeps the angle from leaking into the label inside the ring.
  • A ring reads as progress. If your sections are not completable, this skin sends the wrong signal; use a plain chevron instead.
  • Leave the closing animation alone: ::details-content closes smoothly in Chrome 131+, while other engines snap shut. The ring always reverses, because it is a plain transition.

Browser support

ChromeSafariFirefoxEdge
129+not yetnot yet129+

Floor set by oklch(), color-mix(), @property, transition-behavior, subgrid, interpolate-size as this demo is written. The core technique itself goes back further — Chrome 111+.

@property is Chrome 85 / Safari 16.4 / Firefox 128, the same as Tailwind v4's own floor. The panel height animation needs ::details-content + interpolate-size (Chrome 131+); elsewhere the panel opens instantly while the ring still sweeps.

Techniques used in this demo

Utilitiesfirst-class utility or variant

conic-gradient()tw ↗masktw ↗

Plain CSSno Tailwind surface

@propertytw ↗

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