# Number stepper

Subtle web animation sketch from [https://mighil.com/animations](https://mighil.com/animations).

- **Live demo:** https://mighil.com/animations/number-stepper
- **Standalone HTML:** https://mighil.com/animations/number-stepper?download=1
- **This file:** https://mighil.com/animations/number-stepper/number-stepper.md
- **Technique:** `quantity`

## What it does

Each step bumps the number a bit.

## Instructions for AI / coding agents

Implement this micro-interaction in the user's stack (vanilla HTML, React, Vue, Svelte, etc.).

1. Use the **HTML** as the DOM structure (adapt JSX/templates as needed; keep class names and ids).
2. Include the **Theme** CSS (or map the same variables into the host design system). It switches light/dark with `prefers-color-scheme`.
3. Apply the **CSS** as-is when possible. It uses `var(--text-color)`, `var(--heading-color)`, `var(--background-color)`, etc. from the theme so both modes work.
4. Run the **JavaScript** after the markup mounts. Prefer `DOMContentLoaded` or a framework `useEffect` / `onMount`.
5. Keep motion respectful of `prefers-reduced-motion` if the snippet already checks it.
6. Do not depend on mighil.com runtime or fonts. Theme variables are enough for color.
7. If porting to a component, expose the interactive root via a ref and preserve accessibility attributes (`aria-*`, `role`, `button` types).

## Theme (auto light / dark)

```css
/* Auto light / dark — follows prefers-color-scheme */
:root{
  color-scheme: light dark;
  --text-color: hsl(0, 0%, 18%);
  --heading-color: hsl(0, 0%, 18%);
  --background-color: hsl(0, 0%, 99%);
  --bg-color: hsl(0, 0%, 99%);
  --link-color: hsl(0, 0%, 18%);
  --visited-color: hsl(0, 0%, 18%);
  --blockquote-color: hsl(0, 0%, 18%);
  --code-bg-color: hsl(0, 0%, 95%);
  --code-color: hsl(0, 0%, 18%);
  --sub-color: hsl(0, 0%, 29%);
}
@media (prefers-color-scheme: dark){
:root{
  --text-color: hsl(35, 25%, 85%);
  --heading-color: hsl(35.2, 32.6%, 82.5%);
  --background-color: hsl(60, 2.2%, 8.8%);
  --bg-color: hsl(60, 2.2%, 8.8%);
  --link-color: hsl(34.7, 55.3%, 79.8%);
  --visited-color: hsla(34.7, 55.3%, 79.8%, 0.85);
  --blockquote-color: hsl(35, 30%, 75%);
  --code-bg-color: hsl(30, 5%, 7.8%);
  --code-color: limegreen;
  --sub-color: hsla(34.7, 24.7%, 84.9%, 0.78);
}
}
```

## HTML

```html
<div class="stepper" id="stepper">
        <button type="button" id="stepper-dec" aria-label="Decrease">−</button>
        <span class="stepper-val" id="stepper-val">2</span>
        <button type="button" id="stepper-inc" aria-label="Increase">+</button>
      </div>
```

## CSS

```css
@keyframes stepper-bump{
  0%,100%{transform:scale(1)}
  40%{transform:scale(1.12)}
}

.stepper{display:inline-flex;align-items:center;gap:0;border-radius:8px;overflow:hidden;
  border:1px solid color-mix(in srgb,var(--text-color) 14%,transparent);
}

.stepper button{
  appearance:none;-webkit-appearance:none;width:40px;height:40px;padding:0;cursor:pointer;
  font:inherit;font-size:1.1rem;line-height:1;color:inherit;
  border:0;background:color-mix(in srgb,var(--text-color) 4%,transparent);
}

.stepper button:hover{background:color-mix(in srgb,var(--text-color) 8%,transparent)}

.stepper .stepper-val{
  width:48px;height:40px;display:grid;place-items:center;
  font-size:.95rem;font-weight:500;font-variant-numeric:tabular-nums;
  border-left:1px solid color-mix(in srgb,var(--text-color) 12%,transparent);
  border-right:1px solid color-mix(in srgb,var(--text-color) 12%,transparent);
}

.stepper-val.is-bump{animation:stepper-bump .28s ease-out}

@media (prefers-reduced-motion: reduce){
  .breath-dot,.breath-ring,.wave.is-live span,.ink-drop,
  .marquee-track,
  .skel-line,.save-btn.is-loading .spin,.badge.is-bump,.like-btn.is-pop,.save-status.is-saving .dot,.stars button.is-pop svg,
  .field.is-invalid input,.save-btn.is-done .check path,.ux-check[aria-checked="true"] .ux-box path,.char-meta.is-warn,.success-banner.is-on path,
  .typing span,.conn-dot,.indet > i,.toast.is-on .toast-timer > i,.stagger-list.is-in .stagger-item,.submit-wrap.is-loading .submit-ring rect,.submit-wrap.is-settle,.hold-btn.is-settle,.confirm-btn.is-settle,.sync-btn.is-settle,.invite-btn.is-settle,.retry-btn.is-shake-err,.retry-btn.is-shake-ok,.cart-badge.is-pop,.mute-btn .x-line,.presence.is-ping .presence-dot::after,.tag-chip,.nudge-field.is-nudge,.tilt-scene:hover .tilt-tile::before,.demo-replay.is-tap,.hit.is-tap,.stack-toggle.is-tap,.nudge-btn.is-tap,.wipe.is-tap,.save-btn.is-tap,.copy-btn.is-tap,.like-btn.is-tap,.pin-btn.is-tap,.retry-btn.is-tap,.wizard-nav button.is-tap,.mute-btn.is-tap,
  .scan:hover::after,.scan.is-on::after,.cascade.is-in b,.stepper-val.is-bump,.otp input.is-pop,.rel-time.is-live .rel-dot,.sync-btn.is-spin .sync-arrows,.ok-field.is-ok .ok-check path,.unread-row.is-read .unread-check path,.mic-btn.is-on::before,.mic-btn.is-on::after,.ghost-wrap.is-flash,.cmd-palette li.is-run,.flag-row.is-warn,.mention.is-flash b{animation:none!important}
}
```

## JavaScript

```js
// Number stepper
  const stepperVal = document.getElementById('stepper-val');
  const stepperDec = document.getElementById('stepper-dec');
  const stepperInc = document.getElementById('stepper-inc');
  let stepperN = 2;
  function bumpStepper(next) {
    if (!stepperVal) return;
    stepperN = Math.max(0, Math.min(99, next));
    stepperVal.textContent = String(stepperN);
    stepperVal.classList.remove('is-bump');
    void stepperVal.offsetWidth;
    if (!reduce) stepperVal.classList.add('is-bump');
  }
  if (stepperDec) stepperDec.addEventListener('click', () => bumpStepper(stepperN - 1));
  if (stepperInc) stepperInc.addEventListener('click', () => bumpStepper(stepperN + 1));
```

---

_Source: https://mighil.com/animations/number-stepper_