32 CSS Accordions — Vertical & Horizontal08 / 32

Pure CSSMIT licensed

Numbered Steps Accordion — Process Timeline for Onboarding Flows

An accordion that reads as a process: oversized 01–04 step numerals in circles joined by a vertical connector line, with the open step's circle filling in accent and its number knocked out white. The go-to pattern for onboarding checklists, how-it-works sections and multi-stage service explainers.

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The code

<section class="acc-08" aria-label="Numbered steps accordion demo">
  <div class="acc-08__wrap">
    <p class="acc-08__kicker">Getting started</p>
    <h3 class="acc-08__title">Up and running in four steps</h3>
    <details class="acc-08__step" name="acc-08-steps" open>
      <summary class="acc-08__sum"><span class="acc-08__num">01</span><span class="acc-08__lab">Create your workspace</span></summary>
      <div class="acc-08__body"><p>Pick a workspace URL and invite your first teammates. Everything is soft-deletable for 30 days, so explore freely.</p></div>
    </details>
    <details class="acc-08__step" name="acc-08-steps">
      <summary class="acc-08__sum"><span class="acc-08__num">02</span><span class="acc-08__lab">Connect your data</span></summary>
      <div class="acc-08__body"><p>OAuth into your warehouse or drop a CSV. Schemas are inferred automatically and every column gets a profiling report.</p></div>
    </details>
    <details class="acc-08__step" name="acc-08-steps">
      <summary class="acc-08__sum"><span class="acc-08__num">03</span><span class="acc-08__lab">Build your first dashboard</span></summary>
      <div class="acc-08__body"><p>Start from a template or a blank canvas. Charts stay linked to source queries, so refreshed data flows through instantly.</p></div>
    </details>
    <details class="acc-08__step" name="acc-08-steps">
      <summary class="acc-08__sum"><span class="acc-08__num">04</span><span class="acc-08__lab">Share with your team</span></summary>
      <div class="acc-08__body"><p>Publish to a link, embed in Notion, or schedule a Monday-morning email digest. Viewers don't need a seat.</p></div>
    </details>
  </div>
</section>
.acc-08,
.acc-08 *,
.acc-08 *::before,
.acc-08 *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

.acc-08 {
  --accent: oklch(0.55 0.18 25);
  --dot: 44px;
  --line-w: 2px;
  font-family: 'Segoe UI',system-ui,sans-serif;
  width: 100%;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #faf5f2;
  padding: 40px 20px;
}

.acc-08__wrap {
  width: min(560px,100%);
  background: #fff;
  border-radius: 20px;
  padding: 38px 36px;
  box-shadow: 0 24px 60px -34px rgba(80,30,20,.3);
}

.acc-08__kicker {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--accent);
}

.acc-08__title {
  font-size: 25px;
  font-weight: 800;
  color: #2b1d18;
  letter-spacing: -.02em;
  margin: 6px 0 22px;
}

.acc-08__step {
  position: relative;
  padding-bottom: 8px;
}

.acc-08__step::before {
  content: "";
  position: absolute;
  left: calc(var(--dot)/2 - var(--line-w)/2);
  top: var(--dot);
  bottom: -6px;
  width: var(--line-w);
  background: #eadfd8;
}

.acc-08__step:last-of-type::before {
  display: none;
}

.acc-08__sum {
  list-style: none;
  display: grid;
  grid-template-columns: var(--dot) 1fr;
  align-items: center;
  gap: 16px;
  min-height: 56px;
  cursor: pointer;
}

.acc-08__sum::-webkit-details-marker {
  display: none;
}

.acc-08__sum::marker {
  content: "";
}

.acc-08__num {
  width: var(--dot);
  height: var(--dot);
  display: grid;
  place-content: center;
  border: var(--line-w) solid #e3d4cb;
  border-radius: 50%;
  font-family: ui-monospace,Menlo,monospace;
  font-size: 14px;
  font-weight: 700;
  color: #a08575;
  background: #fff;
  transition: all .3s cubic-bezier(.4,0,.2,1);
  position: relative;
  z-index: 1;
}

.acc-08__lab {
  font-size: 17px;
  font-weight: 700;
  color: #2b1d18;
  transition: color .2s;
}

.acc-08__sum:hover .acc-08__num {
  border-color: var(--accent);
  color: var(--accent);
}

.acc-08__step[open] .acc-08__num {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  transform: scale(1.06);
}

.acc-08__step[open] .acc-08__lab {
  color: var(--accent);
}

.acc-08__body {
  display: grid;
  grid-template-columns: var(--dot) 1fr;
  gap: 16px;
}

.acc-08__body p {
  grid-column: 2;
  padding: 6px 8px 16px 0;
  font-size: 14.5px;
  line-height: 1.65;
  color: #5d4c42;
}

.acc-08__step[open] .acc-08__body {
  animation: acc-08-in .4s cubic-bezier(.2,.7,.3,1);
}

@keyframes acc-08-in {
  from {
    opacity: 0;
    translate: 0 -6px;
  }

  to {
    opacity: 1;
    translate: 0 0;
  }
}

.acc-08__sum:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
  border-radius: 12px;
}

@media (prefers-reduced-motion: reduce) {
  .acc-08__num {
    transition: none;
  }

  .acc-08__step[open] .acc-08__body {
    animation: none;
  }
}
/* No JavaScript — per-item ::before segments draw the timeline connector, details[open] fills the step circle, and name="acc-08-steps" keeps one step focal at a time. */
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 Accordions — Vertical & Horizontal 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: Numbered Steps Accordion — Process Timeline for Onboarding Flows
Source: https://codefronts.com/navigation/css-accordions/numbered-steps/

An accordion that reads as a process: oversized 01–04 step numerals in circles joined by a vertical connector line, with the open step's circle filling in accent and its number knocked out white. The go-to pattern for onboarding checklists, how-it-works sections and multi-stage service explainers.
## HTML
```html
<section class="acc-08" aria-label="Numbered steps accordion demo">
  <div class="acc-08__wrap">
    <p class="acc-08__kicker">Getting started</p>
    <h3 class="acc-08__title">Up and running in four steps</h3>
    <details class="acc-08__step" name="acc-08-steps" open>
      <summary class="acc-08__sum"><span class="acc-08__num">01</span><span class="acc-08__lab">Create your workspace</span></summary>
      <div class="acc-08__body"><p>Pick a workspace URL and invite your first teammates. Everything is soft-deletable for 30 days, so explore freely.</p></div>
    </details>
    <details class="acc-08__step" name="acc-08-steps">
      <summary class="acc-08__sum"><span class="acc-08__num">02</span><span class="acc-08__lab">Connect your data</span></summary>
      <div class="acc-08__body"><p>OAuth into your warehouse or drop a CSV. Schemas are inferred automatically and every column gets a profiling report.</p></div>
    </details>
    <details class="acc-08__step" name="acc-08-steps">
      <summary class="acc-08__sum"><span class="acc-08__num">03</span><span class="acc-08__lab">Build your first dashboard</span></summary>
      <div class="acc-08__body"><p>Start from a template or a blank canvas. Charts stay linked to source queries, so refreshed data flows through instantly.</p></div>
    </details>
    <details class="acc-08__step" name="acc-08-steps">
      <summary class="acc-08__sum"><span class="acc-08__num">04</span><span class="acc-08__lab">Share with your team</span></summary>
      <div class="acc-08__body"><p>Publish to a link, embed in Notion, or schedule a Monday-morning email digest. Viewers don't need a seat.</p></div>
    </details>
  </div>
</section>
```
## CSS
```css
.acc-08,
.acc-08 *,
.acc-08 *::before,
.acc-08 *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

.acc-08 {
  --accent: oklch(0.55 0.18 25);
  --dot: 44px;
  --line-w: 2px;
  font-family: 'Segoe UI',system-ui,sans-serif;
  width: 100%;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #faf5f2;
  padding: 40px 20px;
}

.acc-08__wrap {
  width: min(560px,100%);
  background: #fff;
  border-radius: 20px;
  padding: 38px 36px;
  box-shadow: 0 24px 60px -34px rgba(80,30,20,.3);
}

.acc-08__kicker {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--accent);
}

.acc-08__title {
  font-size: 25px;
  font-weight: 800;
  color: #2b1d18;
  letter-spacing: -.02em;
  margin: 6px 0 22px;
}

.acc-08__step {
  position: relative;
  padding-bottom: 8px;
}

.acc-08__step::before {
  content: "";
  position: absolute;
  left: calc(var(--dot)/2 - var(--line-w)/2);
  top: var(--dot);
  bottom: -6px;
  width: var(--line-w);
  background: #eadfd8;
}

.acc-08__step:last-of-type::before {
  display: none;
}

.acc-08__sum {
  list-style: none;
  display: grid;
  grid-template-columns: var(--dot) 1fr;
  align-items: center;
  gap: 16px;
  min-height: 56px;
  cursor: pointer;
}

.acc-08__sum::-webkit-details-marker {
  display: none;
}

.acc-08__sum::marker {
  content: "";
}

.acc-08__num {
  width: var(--dot);
  height: var(--dot);
  display: grid;
  place-content: center;
  border: var(--line-w) solid #e3d4cb;
  border-radius: 50%;
  font-family: ui-monospace,Menlo,monospace;
  font-size: 14px;
  font-weight: 700;
  color: #a08575;
  background: #fff;
  transition: all .3s cubic-bezier(.4,0,.2,1);
  position: relative;
  z-index: 1;
}

.acc-08__lab {
  font-size: 17px;
  font-weight: 700;
  color: #2b1d18;
  transition: color .2s;
}

.acc-08__sum:hover .acc-08__num {
  border-color: var(--accent);
  color: var(--accent);
}

.acc-08__step[open] .acc-08__num {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  transform: scale(1.06);
}

.acc-08__step[open] .acc-08__lab {
  color: var(--accent);
}

.acc-08__body {
  display: grid;
  grid-template-columns: var(--dot) 1fr;
  gap: 16px;
}

.acc-08__body p {
  grid-column: 2;
  padding: 6px 8px 16px 0;
  font-size: 14.5px;
  line-height: 1.65;
  color: #5d4c42;
}

.acc-08__step[open] .acc-08__body {
  animation: acc-08-in .4s cubic-bezier(.2,.7,.3,1);
}

@keyframes acc-08-in {
  from {
    opacity: 0;
    translate: 0 -6px;
  }

  to {
    opacity: 1;
    translate: 0 0;
  }
}

.acc-08__sum:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 3px;
  border-radius: 12px;
}

@media (prefers-reduced-motion: reduce) {
  .acc-08__num {
    transition: none;
  }

  .acc-08__step[open] .acc-08__body {
    animation: none;
  }
}
```

## JavaScript
```js
/* No JavaScript — per-item ::before segments draw the timeline connector, details[open] fills the step circle, and name="acc-08-steps" keeps one step focal at a time. */
```

How this works

Each step is a <details> whose summary leads with a 44px numbered circle. A vertical connector line is drawn per-item with ::before on the details (top of one circle to top of the next), so steps visually chain into a timeline without any absolute-positioned global line — items remain independently reorderable.

details[open] flips the circle from outlined to solid accent (number knocks out to white) and the step body opens INSIDE the timeline gutter — indented to align with the text, keeping the number column clean. The last item suppresses its connector with :last-of-type::before{display:none}. Exclusive name grouping keeps one step focal at a time, matching how people actually walk through a process.

Techniques used: per-item ::before connector segments (no fragile global line) · outlined→filled circle state flip with color knockout · gutter-aligned body indentation (grid columns) · details name exclusivity for one-focal-step UX · :last-of-type connector suppression

Make it yours

  • Circle size + line thickness = --dot / --line-w tokens.
  • Remove name attributes to let users open several steps for comparison.
  • Completed states: add a class serverside and style the circle green with a check.
  • Numbers are markup, so 'Step 1' vs '01' vs roman numerals is a text edit.

Gotchas — read before shipping

  • Draw connector segments per-item, never one absolute line down the container — open/close changes item heights and a global line drifts out of alignment.
  • Keep the numeral INSIDE the summary (it's part of the click target and the announced text: 'Zero one, Create your workspace').
  • If steps must be completed in order, an accordion is the wrong control — it implies free browsing; use a wizard with disabled future steps instead.
  • The connector is decorative — set nothing meaningful on it; sequence is conveyed by the visible numbers.

Browser support

ChromeSafariFirefoxEdge
120+ for name exclusivity17.2+130+120+ for name exclusivity

The visual pattern works everywhere; only the single-open behavior needs details[name], and multi-open is the graceful fallback.

Techniques used in this demo

<details name="">MDN ↗grid-templateMDN ↗@keyframesMDN ↗place-items / place-contentMDN ↗oklch()MDN ↗

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