# Number Stepper

> A real number input between − and +. Changed digits roll with the count, a held button speeds up, the edge button dims at the limit. Typed values are put back in range on leaving.

Forms · number, stepper, quantity, counter, form · HTML, CSS, vanilla JS · no dependencies · updated 2026-11-04
Demo: https://kodza.dev/components/number-stepper/
Source on GitHub: https://github.com/kodza-dev/kodza/tree/main/components/number-stepper

## Files

The code below, served as files: byte for byte what the Kodza site copies (the CSS includes its theme guard).

- [`kodza-number-stepper.css`](https://kodza.dev/registry/number-stepper/kodza-number-stepper.css) · 20.1 KB
- [`kodza-number-stepper.js`](https://kodza.dev/registry/number-stepper/kodza-number-stepper.js) · 21.2 KB
- [`kodza-number-stepper.html`](https://kodza.dev/registry/number-stepper/kodza-number-stepper.html) · 1.0 KB · the markup, to adapt and paste into your page

**Can you run shell commands? Download the CSS and the JS, don't retype them.** Retyping costs thousands of tokens and can drop or change lines of the CSS. Put the files where your stack expects them (Use it says where: change the `-o` paths):

```bash
curl -fsSL --create-dirs -o kodza/kodza-number-stepper.css https://kodza.dev/registry/number-stepper/kodza-number-stepper.css
curl -fsSL --create-dirs -o kodza/kodza-number-stepper.js https://kodza.dev/registry/number-stepper/kodza-number-stepper.js
```

Then load the files from your page as Use it shows, instead of pasting the content. The HTML is the part you adapt (text, links, modifiers): paste it from the Code section. Copy the CSS and the JS from the Code section only if you can't run commands, exactly as they are. (Windows PowerShell: `curl.exe`.)

## API

- Root: `.kodza-number-stepper`
- Variables (set them on the root element itself: it declares its own defaults):
  - `--kz-number-bg: #ffffff`
  - `--kz-number-fg: #0a0a0a`
  - `--kz-number-muted: rgba(10, 10, 10, 0.6)`
  - `--kz-number-line: rgba(10, 10, 10, 0.14)`
  - `--kz-number-line-hover: rgba(10, 10, 10, 0.3)`
  - `--kz-number-soft: rgba(10, 10, 10, 0.06)`
  - `--kz-number-button: rgba(10, 10, 10, 0.05)` — the − and +
  - `--kz-number-button-hover: rgba(10, 10, 10, 0.09)`
  - `--kz-number-button-press: rgba(10, 10, 10, 0.14)`
  - `--kz-number-error: #0a0a0a` — a message, never colour alone: set a red here if you want one
  - `--kz-number-height: 56px`
  - `--kz-number-radius: calc(12px * var(--kz-radius-scale, 1))`
  - `--kz-number-button-size: 40px`
  - `--kz-number-button-radius: calc(8px * var(--kz-radius-scale, 1))`
  - `--kz-number-value-size: 17px`
  - `--kz-number-width: var(--kz-field-width, 240px)`
  - `--kz-number-duration: 0.28s`
  - `--kz-number-ease: cubic-bezier(0.22, 1, 0.36, 1)`
- Modifiers: `.kodza-number-stepper--compact`
- Lifecycle: `kodza:init` / `kodza:destroy` on `document`, with `{ detail: { root } }` to target a container.

## Keyboard

What each key does, by where the focus is. Keep it working when you adapt the HTML: same elements, same classes.

- In the field (focus in `.kodza-number-stepper__input`):
  - `ArrowUp` / `ArrowDown`: One step up or down, the digits roll
  - `PageUp` / `PageDown`: Ten steps at once
  - `Home` / `End`: The min or the max, when the field has one
  - `Enter`: Puts a typed value back in range, then submits

## Dark mode

The values Kodza uses on a dark background (`#0a0a0a`). For a page that follows the system theme, add them after the component's CSS:

```css
@media (prefers-color-scheme: dark) {
  .kodza-number-stepper {
    --kz-number-bg: #161616;
    --kz-number-fg: #f2f2f0;
    --kz-number-muted: rgba(242, 242, 240, 0.62);
    --kz-number-line: rgba(255, 255, 255, 0.14);
    --kz-number-line-hover: rgba(255, 255, 255, 0.3);
    --kz-number-soft: rgba(255, 255, 255, 0.08);
    --kz-number-button: rgba(255, 255, 255, 0.07);
    --kz-number-button-hover: rgba(255, 255, 255, 0.12);
    --kz-number-button-press: rgba(255, 255, 255, 0.18);
    --kz-number-error: #f2f2f0;
  }
}
```

A site with its own theme switch puts the same rules under its dark selector instead (`[data-theme="dark"] .kodza-number-stepper { … }`); a single dark section, under that section's class.

## Use it

### Plain HTML page

- CSS: `kodza/kodza-number-stepper.css` next to the page (the Files commands as they are), linked in `<head>`: `<link rel="stylesheet" href="kodza/kodza-number-stepper.css">`. Without a shell, paste it in a `<style>` in `<head>` instead. It only touches `kodza-` classes.
- HTML: where the component goes. Paste it as many times as you need: instances never interfere.
- JS: `kodza/kodza-number-stepper.js`, loaded with `<script src="kodza/kodza-number-stepper.js" defer></script>` in `<head>`. Without a shell, paste it in a `<script>` before `</body>` (or in `<head>`: it waits for the page). One copy per page, whatever the number of instances.
- Restyle with the `--kz-…` variables, set on the component's root element itself (the root declares its own defaults, so a value on an ancestor is ignored), and with the modifiers / attributes listed under API.
- Font: it takes the page's own. A site with its own type sets it once for every Kodza component, on `:root`, never by editing the CSS (unset, nothing changes): `--kz-font-label`, the face of the small labels (meta, captions, counters, hints, footer links, button labels); `--kz-font-label-size`, their size, one for all of them (`11px`…); `--kz-font-label-weight`, their weight; `--kz-font-label-tracking`, their letter-spacing; `--kz-font-label-case`, their case (`uppercase`…; code and units keep theirs); `--kz-font-label-leading`, their line-height (`1.45`…; buttons, pills and keys keep their box). The Kodza look is Geist: `<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Geist:wght@400;500;600;700&family=Geist+Mono:wght@400;500&display=swap">`.
- Corners: a site with its own shapes sets them once for every Kodza component, on `:root`, never by editing the CSS (unset, nothing changes): `--kz-radius-scale` multiplies every corner (`0` square, `0.5` softer, `1` Kodza); `--kz-radius-pill` sets the pills (`0` squares them).
- Width: a form sets it once for every Kodza field, on the form or on `:root` (`--kz-field-width: 100%` fills the column). Unset, nothing changes.
- Motion: a site sets its pace once for every Kodza component, on `:root`, never by editing the CSS or the JS: `--kz-motion-scale` multiplies every duration (`0.5` twice as fast, `2` twice as slow, `0` no motion at all, loops stopped, like reduced motion). Unset, nothing changes.
- Content added later (AJAX navigation, a SPA route, a builder preview): start it with `document.dispatchEvent(new CustomEvent('kodza:init', { detail: { root: container } }))`; before removing it, the same call with `'kodza:destroy'` stops it and puts the original markup back.

### Claude artifact (claude.ai)

- Paste the CSS in a `<style>` and the JS in a `<script>` at the end, in the artifact itself: it loads stylesheets only from Google Fonts and scripts only from a few CDNs, so no `<link>` or `<script src>` to Kodza.
- Writing the artifact file with a shell? Insert the downloaded files (Files) with a command instead of retyping them: a line `KODZA-CSS` alone inside the `<style>`, `KODZA-JS` inside the `<script>`, then `sed -e '/^KODZA-CSS$/{r kodza/kodza-number-stepper.css' -e 'd' -e '}' -e '/^KODZA-JS$/{r kodza/kodza-number-stepper.js' -e 'd' -e '}' page.html > artifact.html`.
- Font: load Geist from Google Fonts (allowed): `<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Geist:wght@400;500;600;700&family=Geist+Mono:wght@400;500&display=swap">`. A site with its own type sets it once for every Kodza component, on `:root`, never by editing the CSS (unset, nothing changes): `--kz-font-label`, the face of the small labels (meta, captions, counters, hints, footer links, button labels); `--kz-font-label-size`, their size, one for all of them (`11px`…); `--kz-font-label-weight`, their weight; `--kz-font-label-tracking`, their letter-spacing; `--kz-font-label-case`, their case (`uppercase`…; code and units keep theirs); `--kz-font-label-leading`, their line-height (`1.45`…; buttons, pills and keys keep their box).
- Corners: a site with its own shapes sets them once for every Kodza component, on `:root`, never by editing the CSS (unset, nothing changes): `--kz-radius-scale` multiplies every corner (`0` square, `0.5` softer, `1` Kodza); `--kz-radius-pill` sets the pills (`0` squares them).
- Width: a form sets it once for every Kodza field, on the form or on `:root` (`--kz-field-width: 100%` fills the column). Unset, nothing changes.
- Motion: a site sets its pace once for every Kodza component, on `:root`, never by editing the CSS or the JS: `--kz-motion-scale` multiplies every duration (`0.5` twice as fast, `2` twice as slow, `0` no motion at all, loops stopped, like reduced motion). Unset, nothing changes.
- Dark mode: the viewer sets `data-theme="dark"` or `"light"` on `<html>`, or nothing when it follows the system. Write the Dark mode rules twice: inside `@media (prefers-color-scheme: dark)` with `:root:not([data-theme="light"])` in front of each selector, and with `:root[data-theme="dark"]` in front of each selector.
- Forms: there is nowhere to send them. Handle `submit` in your script with `event.preventDefault()` and show the result in the page.

### WordPress

- HTML: a **Custom HTML** block (or a pattern / template part). WordPress keeps this markup as it is only for users allowed to post unfiltered HTML (Administrators; Super Admins on multisite): for anyone else it strips tags such as `<svg>`, `<input>` or `<dialog>`, so add it from the theme (a pattern or template part) instead.
- CSS and JS: the downloaded files go in the theme, under `wp-content/themes/<your-theme>/kodza/` (the child theme if there is one), enqueued from its functions.php (or a code-snippets plugin):
  ```php
  add_action('wp_enqueue_scripts', function () {
    $dir = get_stylesheet_directory() . '/kodza/';
    $uri = get_stylesheet_directory_uri() . '/kodza/';
    wp_enqueue_style('kodza-number-stepper', $uri . 'kodza-number-stepper.css', [], filemtime($dir . 'kodza-number-stepper.css'));
    wp_enqueue_script('kodza-number-stepper', $uri . 'kodza-number-stepper.js', [], filemtime($dir . 'kodza-number-stepper.js'), true);
  });
  ```
  Scoped to `kodza-` classes, the CSS never touches the theme. One copy of the JS, whatever the number of blocks.
- No access to the theme files? The CSS can also go, as it is, in **Appearance → Customize → Additional CSS** (classic theme) or **Styles → Additional CSS** in the Site Editor (block theme).
- Theme with AJAX page transitions: fire `kodza:init` on the new content after each swap (and `kodza:destroy` on the old one).
- Performance plugin (WP Rocket, LiteSpeed Cache, Perfmatters…) with **Delay JavaScript execution** turned on: add `kodza` to the scripts it must not delay. Otherwise the component waits for the visitor's first scroll, tap or mouse move, and that first click can be lost.
- Colours: by default, match the theme's palette. After the component's CSS, point these variables at the theme's colours, on the component root, Kodza's value as the fallback:
  `.kodza-number-stepper { --kz-number-fg: var(TEXT, #0a0a0a); --kz-number-bg: var(BACKGROUND, #ffffff); }`
  TEXT, BACKGROUND and ACCENT (the colour the theme fills its own buttons with) are the theme's own colour variables — block themes (theme.json, like Twenty Twenty-Five): `--wp--preset--color--contrast`, `--wp--preset--color--base`, `--wp--preset--color--contrast` (they fill their buttons with it; their accent-1… colours are decorative); Astra: `--ast-global-color-2`, `--ast-global-color-4`, `--ast-global-color-0`; Kadence: `--global-palette3`, `--global-palette9`, `--global-palette1`; GeneratePress: `--contrast`, `--base-3`, `--accent`; Blocksy: `--theme-palette-color-4`, `--theme-palette-color-8`, `--theme-palette-color-1`. Use only these names, and only if the site really has them (the theme's CSS, or Styles → Colors): the `--wp--preset--color--black`, `--white`, `--vivid-…` that WordPress adds everywhere are not the theme's palette. Another theme, or one without these variables (Hello Elementor, OceanWP): leave the variables alone, it keeps Kodza's monochrome; same when the developer asks for monochrome or the Kodza look. Leave the translucent greys (`rgba(10, 10, 10, …)`) as they are: they suit any light background. On a dark palette, set the other variables from Dark mode too.
- WordPress turns straight quotes and `--` into typographic ones in the text of a Custom HTML block (not inside `<code>` or `<pre>`).

#### With Elementor

- HTML: an **HTML** widget (Elementor shows it to administrators only). It keeps the code exactly as pasted, straight quotes included.
- CSS and JS: as above. Elementor's Site Settings → Theme Style styles every button, field, link and image of the page, components included; the theme guard at the end of the CSS keeps the component's buttons, fields and link colours as they are.
- The Elementor editor redraws each widget after the page has loaded: without the script below, the component stays still in the editor preview (the published page works). Add it once per site, in the footer like the component's script (`kodza/elementor-editor.js`, or a code-snippets plugin):

```js
// Kodza in the Elementor editor: the editor redraws each HTML widget after the page has loaded.
// Start Kodza in what it draws, stop it in what it replaces or removes. Once per site.
window.addEventListener('elementor/frontend/init', () => {
  if (!elementorFrontend.isEditMode()) return;
  class KodzaWidget extends elementorModules.frontend.handlers.Base {
    onInit() {
      super.onInit();
      this.kodza = [...this.$element[0].children];
      document.dispatchEvent(new CustomEvent('kodza:init', { detail: { root: this.$element[0] } }));
    }
    onDestroy() {
      super.onDestroy();
      this.kodza.forEach((root) => document.dispatchEvent(new CustomEvent('kodza:destroy', { detail: { root } })));
    }
  }
  elementorFrontend.elementsHandler.attachHandler('html', KodzaWidget);
});
```

- No child theme: everything can go in the HTML widget instead, `<style>` with the CSS, the HTML, then `<script>` with the JS. It works on the page and in the editor without the script above.

### Shopify

- Files: `assets/kodza-number-stepper.css` and `assets/kodza-number-stepper.js` (the Files commands with `-o assets/…`).
- In the section: `{{ 'kodza-number-stepper.css' | asset_url | stylesheet_tag }}` and `<script src="{{ 'kodza-number-stepper.js' | asset_url }}" defer></script>`, then the HTML.
- The theme editor re-renders sections: restart them with
  `document.addEventListener('shopify:section:load', (e) => document.dispatchEvent(new CustomEvent('kodza:init', { detail: { root: e.target } })));`
  and the same with `shopify:section:unload` → `kodza:destroy`.

### React / Next.js

- Files, side by side (e.g. in `components/kodza/`): `NumberStepper.tsx` (below), the CSS block under Code saved as `number-stepper.css` and the JS block as `number-stepper.js`, both as they are. The HTML block is already inside the component: skip it.
- Use it: `import { NumberStepper } from '@/components/kodza/NumberStepper';` then `<NumberStepper />`. Props: `variant` ("compact", or several in an array), `vars` (the `--kz-…` variables listed under API, e.g. `vars={{ '--kz-number-bg': … }}`), `className`, `style` and the other props of its `<div>` (`onClick`, `aria-…`).
- Next.js App Router: it is a Client Component already (`'use client'`). Pages Router: Next.js takes global CSS only in `pages/_app`, so move the `import './number-stepper.css'` line there.
- Safe under StrictMode, client-side navigation and prop changes: when a prop changes, the `key` gives React a fresh element, `kodza:destroy` stops the script on the old one and `kodza:init` starts it on the new one.
- Built from your data (tabs, rows, options)? Add what the markup is made of to the `key`, as plain values (ids, text, numbers). What the visitor changes (the open tab, the sort, what they type) is the script's: follow it with `onClick` or `onInput` on the root, and change it from your code as a visitor would (click the tab; set the field's value, then dispatch a bubbling `input` event). Fields stay uncontrolled (`defaultValue`, `name`).

```tsx
'use client';
// Kodza — Number Stepper, for React. From https://kodza.dev/components/number-stepper/
// Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license
// Next to this file: number-stepper.css and number-stepper.js, the component's CSS and JS from Kodza, as they are.
// Yours to edit: the markup is plain JSX below.
// The script changes this markup once React has rendered it (it adds layers, splits text, moves
// nodes), so React must not patch it afterwards. When a prop changes, the key gives React a fresh
// element: kodza:destroy stops the script on the old one, kodza:init starts it on the new one.
// data-kodza-manual keeps the script from starting it on its own: the effect below does, once
// React has hydrated the markup (on a page that streams in, the script can load first).
// Built from your data (tabs, rows, options)? Put what the markup is made of in the key, as plain
// values (ids, text, numbers): a change starts the script again on fresh markup. What the visitor
// changes (the open tab, the sort, what they type) is the script's: keep it out of the key, follow
// it with onClick or onInput on the root, and change it from your code as a visitor would (click
// the tab; set the field's value, then dispatch a bubbling input event).
import { useRef, useEffect, type ComponentPropsWithoutRef, type ComponentRef, type CSSProperties } from 'react';
import './number-stepper.css';

type Variant = "compact";

export type NumberStepperProps = Omit<ComponentPropsWithoutRef<'div'>, "children" | "variant" | "vars"> & {
  /** Modifier class(es): .kodza-number-stepper--compact */
  variant?: Variant | Variant[];
  /** Settings, as CSS variables on the root */
  vars?: {
    /** default: #ffffff */
    "--kz-number-bg"?: string | number;
    /** default: #0a0a0a */
    "--kz-number-fg"?: string | number;
    /** default: rgba(10, 10, 10, 0.6) */
    "--kz-number-muted"?: string | number;
    /** default: rgba(10, 10, 10, 0.14) */
    "--kz-number-line"?: string | number;
    /** default: rgba(10, 10, 10, 0.3) */
    "--kz-number-line-hover"?: string | number;
    /** default: rgba(10, 10, 10, 0.06) */
    "--kz-number-soft"?: string | number;
    /** the − and + — default: rgba(10, 10, 10, 0.05) */
    "--kz-number-button"?: string | number;
    /** default: rgba(10, 10, 10, 0.09) */
    "--kz-number-button-hover"?: string | number;
    /** default: rgba(10, 10, 10, 0.14) */
    "--kz-number-button-press"?: string | number;
    /** a message, never colour alone: set a red here if you want one — default: #0a0a0a */
    "--kz-number-error"?: string | number;
    /** default: 56px */
    "--kz-number-height"?: string | number;
    /** default: calc(12px * var(--kz-radius-scale, 1)) */
    "--kz-number-radius"?: string | number;
    /** default: 40px */
    "--kz-number-button-size"?: string | number;
    /** default: calc(8px * var(--kz-radius-scale, 1)) */
    "--kz-number-button-radius"?: string | number;
    /** default: 17px */
    "--kz-number-value-size"?: string | number;
    /** default: var(--kz-field-width, 240px) */
    "--kz-number-width"?: string | number;
    /** default: 0.28s */
    "--kz-number-duration"?: string | number;
    /** default: cubic-bezier(0.22, 1, 0.36, 1) */
    "--kz-number-ease"?: string | number;
  };
  className?: string;
};

export function NumberStepper({ variant, vars, className, style, ...rest }: NumberStepperProps) {
  const ref = useRef<ComponentRef<'div'>>(null);
  const classes = ["kodza-number-stepper", ...([] as string[]).concat(variant ?? []).map((v) => `kodza-number-stepper--${v}`), className].filter(Boolean).join(' ');
  // Everything the markup is made of: when it changes, React gets a fresh element (see the top)
  const key = JSON.stringify([classes, vars, style, rest]);

  // Starts the script on this element once React has rendered it, stops it when it goes
  useEffect(() => {
    const root = ref.current;
    let live = true;
    // @ts-ignore: a plain script, no types to find
    import('./number-stepper.js').then(() => {
      if (live) document.dispatchEvent(new CustomEvent('kodza:init', { detail: { root } }));
    });
    return () => {
      live = false;
      document.dispatchEvent(new CustomEvent('kodza:destroy', { detail: { root } }));
    };
  }, [key]);

  return (
    <div key={key} {...rest} className={classes} data-kodza-manual style={{ ...vars, ...style } as CSSProperties} ref={ref}>
      <label className="kodza-number-stepper__box">
        <span className="kodza-number-stepper__label">Guests</span>
        {' '}
        <input className="kodza-number-stepper__input" type="number" name="guests" defaultValue="2" min="1" max="12" step="1" inputMode="numeric" />
      </label>
      <p className="kodza-number-stepper__note">
        <span className="kodza-number-stepper__hint">Up to 12. The sofa folds out.</span>
        {' '}
        <span className="kodza-number-stepper__error" aria-live="polite" />
      </p>
    </div>
  );
}
```

## Code

```html
<div class="kodza-number-stepper">
  <label class="kodza-number-stepper__box">
    <span class="kodza-number-stepper__label">Guests</span>
    <input class="kodza-number-stepper__input" type="number" name="guests" value="2" min="1" max="12" step="1" inputmode="numeric">
  </label>
  <p class="kodza-number-stepper__note">
    <span class="kodza-number-stepper__hint">Up to 12. The sofa folds out.</span>
    <span class="kodza-number-stepper__error" aria-live="polite"></span>
  </p>
</div>

<div class="kodza-number-stepper kodza-number-stepper--compact">
  <label class="kodza-number-stepper__box">
    <span class="kodza-number-stepper__label">Quantity</span>
    <input class="kodza-number-stepper__input" type="number" name="quantity" value="1" min="1" max="5" step="1" inputmode="numeric">
  </label>
  <p class="kodza-number-stepper__note">
    <span class="kodza-number-stepper__hint">5 left.</span>
    <span class="kodza-number-stepper__error" aria-live="polite"></span>
  </p>
</div>
```

```css
/* Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license */
/* Kodza — Number Stepper
   A real number input between − and +. Each digit that changes rolls, up as the count goes up,
   down as it goes down; a new place (9 to 10) opens its room as its digit rolls in. Holding a
   button speeds up, the button at the edge goes dim at the limit, and typing stays possible:
   out of range, the error says why, and on leaving the field the value rolls back into range.
   Without JS, the native input stays, styled, with its own arrows. Same box as Text Field.
   Everything is tuned with the --kz-number-* variables; the words and timings, at the top of
   the script. */
.kodza-number-stepper {
  --kz-number-bg: #ffffff;
  --kz-number-fg: #0a0a0a;
  --kz-number-muted: rgba(10, 10, 10, 0.6);
  --kz-number-line: rgba(10, 10, 10, 0.14);
  --kz-number-line-hover: rgba(10, 10, 10, 0.3);
  --kz-number-soft: rgba(10, 10, 10, 0.06);
  --kz-number-button: rgba(10, 10, 10, 0.05); /* the − and + */
  --kz-number-button-hover: rgba(10, 10, 10, 0.09);
  --kz-number-button-press: rgba(10, 10, 10, 0.14);
  --kz-number-error: #0a0a0a; /* a message, never colour alone: set a red here if you want one */
  --kz-number-height: 56px;
  --kz-number-radius: calc(12px * var(--kz-radius-scale, 1));
  --kz-number-button-size: 40px;
  --kz-number-button-radius: calc(8px * var(--kz-radius-scale, 1));
  --kz-number-value-size: 17px;
  --kz-number-width: var(--kz-field-width, 240px);
  --kz-number-duration: 0.28s;
  --kz-number-ease: cubic-bezier(0.22, 1, 0.36, 1);

  position: relative;
  display: grid;
  gap: 8px;
  width: 100%;
  max-width: var(--kz-number-width);
  color: var(--kz-number-fg);
}

/* The compact one, for a cart line: a pill with round buttons, the label kept for screen readers */
.kodza-number-stepper--compact {
  --kz-number-height: 44px;
  --kz-number-radius: var(--kz-radius-pill, 999px);
  --kz-number-button-size: 36px;
  --kz-number-button-radius: var(--kz-radius-pill, 999px);
  --kz-number-value-size: 15px;
  --kz-number-width: 136px;
}

/* The box: label on top, the number below (and the native arrows, without the script) */
.kodza-number-stepper__box {
  position: relative;
  display: block;
  box-sizing: border-box;
  height: var(--kz-number-height);
  margin: 0;
  padding: 0;
  border-radius: var(--kz-number-radius);
  background: var(--kz-number-bg);
  box-shadow: inset 0 0 0 1px var(--kz-number-line);
  cursor: text;
  transition: box-shadow calc(0.25s * var(--kz-motion-scale, 1)) ease;
}

.kodza-number-stepper__box:hover,
.kodza-number-stepper:has(.kodza-number-stepper__button:hover:not(:disabled)) .kodza-number-stepper__box {
  box-shadow: inset 0 0 0 1px var(--kz-number-line-hover);
}

.kodza-number-stepper__box:focus-within {
  box-shadow: inset 0 0 0 1.5px var(--kz-number-fg), 0 0 0 4px var(--kz-number-soft);
}

.kodza-number-stepper.is-invalid .kodza-number-stepper__box {
  box-shadow: inset 0 0 0 1.5px var(--kz-number-error);
}

.kodza-number-stepper.is-invalid .kodza-number-stepper__box:focus-within {
  box-shadow: inset 0 0 0 1.5px var(--kz-number-error), 0 0 0 4px var(--kz-number-soft);
}

.kodza-number-stepper.is-disabled .kodza-number-stepper__box {
  opacity: 0.5;
  cursor: not-allowed;
}

.kodza-number-stepper__label {
  position: absolute;
  top: 10px;
  left: 16px;
  z-index: 2;
  color: var(--kz-number-muted);
  font-size: 12px;
  line-height: 1;
  white-space: nowrap;
  pointer-events: none;
}

.kodza-number-stepper__input {
  display: block;
  box-sizing: border-box;
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 25px 16px 9px;
  border: 0;
  border-radius: inherit;
  background: none;
  color: inherit;
  font: inherit;
  font-size: 15px;
  line-height: 22px;
  font-variant-numeric: tabular-nums;
  outline: none;
}

.kodza-number-stepper__input:disabled {
  cursor: not-allowed;
}

/* With the script: − on the left, + on the right, label and number centred between them. The
   input is still there, on top, its text hidden behind the digits that roll; typing shows it */
.kodza-number-stepper.is-ready .kodza-number-stepper__box {
  --kz-number-inset: calc((var(--kz-number-height) - var(--kz-number-button-size)) / 2);
  --kz-number-side: calc(var(--kz-number-button-size) + var(--kz-number-inset) * 2);
}

.kodza-number-stepper.is-ready .kodza-number-stepper__label {
  right: var(--kz-number-side);
  left: var(--kz-number-side);
  overflow: hidden;
  text-align: center;
  text-overflow: ellipsis;
}

.kodza-number-stepper.is-ready .kodza-number-stepper__input,
.kodza-number-stepper__value {
  font-size: var(--kz-number-value-size);
  font-weight: 500;
  letter-spacing: -0.01em;
  text-align: center;
}

.kodza-number-stepper.is-ready .kodza-number-stepper__input {
  position: relative;
  z-index: 1;
  padding: 25px var(--kz-number-side) 9px;
  color: transparent;
  caret-color: var(--kz-number-fg);
  -moz-appearance: textfield;
  appearance: textfield;
}

.kodza-number-stepper.is-ready .kodza-number-stepper__input::-webkit-inner-spin-button,
.kodza-number-stepper.is-ready .kodza-number-stepper__input::-webkit-outer-spin-button {
  margin: 0;
  -webkit-appearance: none;
  appearance: none;
}

/* While typing, the input's own text, exactly where the digits were */
.kodza-number-stepper.is-typing .kodza-number-stepper__input {
  color: inherit;
}

.kodza-number-stepper.is-typing .kodza-number-stepper__value {
  visibility: hidden;
}

/* The digits: one slot per place, each its own window, so only the digits that change roll */
.kodza-number-stepper__value {
  position: absolute;
  right: var(--kz-number-side);
  bottom: 9px;
  left: var(--kz-number-side);
  display: flex;
  justify-content: center;
  height: 22px;
  line-height: 22px;
  font-variant-numeric: tabular-nums;
  white-space: pre;
  pointer-events: none;
}

.kodza-number-stepper__digit {
  display: inline-grid;
  overflow: hidden;
}

.kodza-number-stepper__digit > span {
  grid-area: 1 / 1;
}

/* Compact: no visible label, the number in the middle */
.kodza-number-stepper--compact .kodza-number-stepper__label {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

.kodza-number-stepper--compact .kodza-number-stepper__input {
  padding: 11px 16px;
}

.kodza-number-stepper--compact.is-ready .kodza-number-stepper__input {
  padding: 11px var(--kz-number-side);
}

.kodza-number-stepper--compact .kodza-number-stepper__value {
  bottom: 11px;
}

/* − and +: tactile squares in the box (round in the compact one), dim at the limit */
.kodza-number-stepper__button {
  position: absolute;
  top: var(--kz-number-inset);
  z-index: 2;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  width: var(--kz-number-button-size);
  height: var(--kz-number-button-size);
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: var(--kz-number-button-radius);
  background: var(--kz-number-button);
  color: var(--kz-number-fg);
  font: inherit;
  cursor: pointer;
  touch-action: manipulation;
  user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
  -webkit-tap-highlight-color: transparent;
  transition:
    background-color calc(0.15s * var(--kz-motion-scale, 1)) ease,
    transform calc(0.15s * var(--kz-motion-scale, 1)) var(--kz-number-ease);
}

.kodza-number-stepper.is-ready .kodza-number-stepper__button {
  --kz-number-inset: calc((var(--kz-number-height) - var(--kz-number-button-size)) / 2);
}

.kodza-number-stepper__minus {
  left: var(--kz-number-inset);
}

.kodza-number-stepper__plus {
  right: var(--kz-number-inset);
}

.kodza-number-stepper__button svg {
  width: 14px;
  height: 14px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-width: 1.5;
  transition: opacity calc(0.2s * var(--kz-motion-scale, 1)) ease;
}

@media (hover: hover) {
  .kodza-number-stepper__button:hover:not(:disabled) {
    background: var(--kz-number-button-hover);
  }
}

/* Pressed: by the pointer, or by the arrow key that does the same thing */
.kodza-number-stepper__button.is-pressed {
  background: var(--kz-number-button-press);
  transform: scale(0.92);
}

.kodza-number-stepper__button:disabled {
  background: transparent;
  cursor: not-allowed;
}

.kodza-number-stepper__button:disabled svg {
  opacity: 0.28;
}

.kodza-number-stepper.is-disabled .kodza-number-stepper__button {
  opacity: 0.5;
}

/* Hint and error share one line: the hint steps out upward as the error rises in */
.kodza-number-stepper__note {
  display: grid;
  margin: 0;
  padding: 0 2px;
  overflow: hidden;
  font-family: var(--kz-font-label, inherit);
  font-size: var(--kz-font-label-size, 13px);
  font-weight: var(--kz-font-label-weight, inherit);
  letter-spacing: var(--kz-font-label-tracking, inherit);
  line-height: var(--kz-font-label-leading, 1.4);
  text-transform: var(--kz-font-label-case, inherit);
}

.kodza-number-stepper__hint,
.kodza-number-stepper__error {
  grid-area: 1 / 1;
  transition:
    opacity calc(0.22s * var(--kz-motion-scale, 1)) ease,
    transform calc(0.35s * var(--kz-motion-scale, 1)) var(--kz-number-ease);
}

.kodza-number-stepper__hint {
  color: var(--kz-number-muted);
}

.kodza-number-stepper__error {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--kz-number-error);
  font-weight: var(--kz-font-label-weight, 500);
  opacity: 0;
  transform: translateY(100%);
}

.kodza-number-stepper__error::before {
  content: "";
  flex: none;
  width: 14px;
  height: 14px;
  background: currentColor;
  -webkit-mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3E%3Ccircle cx='8' cy='8' r='6.5' fill='none' stroke='black' stroke-width='1.5'/%3E%3Cpath d='M8 4.5v4.2M8 10.9v.1' stroke='black' stroke-width='1.6' stroke-linecap='round'/%3E%3C/svg%3E") center / contain no-repeat;
  mask: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3E%3Ccircle cx='8' cy='8' r='6.5' fill='none' stroke='black' stroke-width='1.5'/%3E%3Cpath d='M8 4.5v4.2M8 10.9v.1' stroke='black' stroke-width='1.6' stroke-linecap='round'/%3E%3C/svg%3E") center / contain no-repeat;
}

.kodza-number-stepper.is-invalid .kodza-number-stepper__hint {
  opacity: 0;
  transform: translateY(-100%);
}

.kodza-number-stepper.is-invalid .kodza-number-stepper__error {
  opacity: 1;
  transform: none;
}

/* What screen readers hear after a press on − or +: the new value */
.kodza-number-stepper__live {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

@media (prefers-reduced-motion: reduce) {
  .kodza-number-stepper__box,
  .kodza-number-stepper__button,
  .kodza-number-stepper__button svg,
  .kodza-number-stepper__hint,
  .kodza-number-stepper__error {
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
  }
}

/* Theming example — on a dark background:
.dark-section .kodza-number-stepper {
  --kz-number-bg: #161616;
  --kz-number-fg: #f2f2f0;
  --kz-number-muted: rgba(242, 242, 240, 0.62);
  --kz-number-line: rgba(255, 255, 255, 0.14);
  --kz-number-line-hover: rgba(255, 255, 255, 0.3);
  --kz-number-soft: rgba(255, 255, 255, 0.08);
  --kz-number-button: rgba(255, 255, 255, 0.07);
  --kz-number-button-hover: rgba(255, 255, 255, 0.12);
  --kz-number-button-press: rgba(255, 255, 255, 0.18);
  --kz-number-error: #f2f2f0;
}
*/

/* kodza-guard 981055c608ea — generated by Kodza, do not edit.
   Theme guard: keeps a site's own CSS (WordPress themes, Bootstrap, CSS resets…) off this
   component. :not(#_) is always true and weighs as much as an id, so these lines win over
   theme rules made of classes and tags. Customise the component through its --kz-* variables. */

/* What the browser gives, where the component sets it only in some states: at the lowest weight, so its own rules below put it back */

:where(.kodza-number-stepper__input):not(#_) {
  position: revert;
  appearance: revert;
  letter-spacing: revert;
  text-align: revert;
}

/* What the browser gives, on everything the component leaves to it */

.kodza-number-stepper:not(#_),
.kodza-number-stepper__label:not(#_),
.kodza-number-stepper__value:not(#_),
.kodza-number-stepper__digit:not(#_),
.kodza-number-stepper__hint:not(#_),
.kodza-number-stepper__error:not(#_),
.kodza-number-stepper__live:not(#_),
.kodza-number-stepper__digit span:where(:not([class*="kodza-"])):not(#_) {
  box-sizing: revert;
}

.kodza-number-stepper__box:not(#_) {
  border: revert;
  outline: revert;
  text-decoration: revert;
  list-style: revert;
  float: revert;
  outline-offset: revert;
  appearance: revert;
  max-width: revert;
  max-height: revert;
  color: revert;
  font-family: revert;
  font-size: revert;
  font-weight: revert;
  font-style: revert;
  line-height: revert;
  letter-spacing: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-number-stepper__input:not(#_) {
  text-decoration: revert;
  transition: revert;
  list-style: revert;
  float: revert;
  box-shadow: revert;
  outline-offset: revert;
  max-width: revert;
  max-height: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
  white-space: revert;
  min-height: revert;
}

.kodza-number-stepper__button:not(#_) {
  outline: revert;
  text-decoration: revert;
  list-style: revert;
  float: revert;
  box-shadow: revert;
  outline-offset: revert;
  appearance: revert;
  max-width: revert;
  max-height: revert;
  letter-spacing: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
  white-space: revert;
  min-height: revert;
}

.kodza-number-stepper__note:not(#_) {
  border: revert;
  border-radius: revert;
  outline: revert;
  text-decoration: revert;
  transition: revert;
  list-style: revert;
  box-sizing: revert;
  float: revert;
  background-color: revert;
  background-image: revert;
  box-shadow: revert;
  outline-offset: revert;
  appearance: revert;
  max-width: revert;
  max-height: revert;
  color: revert;
  font-style: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-number-stepper__button svg:where(:not([class*="kodza-"])):not(#_) {
  border: revert;
  margin: revert;
  padding: revert;
  border-radius: revert;
  outline: revert;
  text-decoration: revert;
  list-style: revert;
  box-sizing: revert;
  float: revert;
  position: revert;
  background-color: revert;
  background-image: revert;
  box-shadow: revert;
  outline-offset: revert;
  appearance: revert;
  max-width: revert;
  max-height: revert;
  color: revert;
  font-family: revert;
  font-size: revert;
  font-weight: revert;
  font-style: revert;
  line-height: revert;
  letter-spacing: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-number-stepper__button svg:where(:not([class*="kodza-"])):not(#_):where(:not([hidden])) {
  display: revert;
}

.kodza-number-stepper__button svg:where(:not([class*="kodza-"])):not(#_):where([hidden]) {
  display: none;
}

.kodza-number-stepper__error:not(#_)::before {
  box-sizing: revert;
}

/* The component's own rules, one step stronger: real buttons and fields, what it sets on tags themes style (links, lists, headings, images…), and the root width (a theme may narrow it, never widen it) */

.kodza-number-stepper:not(#_) {
  width: min(100%, var(--kz-number-width));
}

.kodza-number-stepper__box:not(#_) {
  position: relative;
  display: block;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  border-radius: var(--kz-number-radius);
  background: var(--kz-number-bg);
  box-shadow: inset 0 0 0 1px var(--kz-number-line);
  transition: box-shadow calc(0.25s * var(--kz-motion-scale, 1)) ease;
}

.kodza-number-stepper__box:hover:not(#_),
.kodza-number-stepper:has(.kodza-number-stepper__button:hover:not(:disabled)) .kodza-number-stepper__box:not(#_) {
  box-shadow: inset 0 0 0 1px var(--kz-number-line-hover);
}

.kodza-number-stepper__box:focus-within:not(#_) {
  box-shadow: inset 0 0 0 1.5px var(--kz-number-fg), 0 0 0 4px var(--kz-number-soft);
}

.kodza-number-stepper.is-invalid .kodza-number-stepper__box:not(#_) {
  box-shadow: inset 0 0 0 1.5px var(--kz-number-error);
}

.kodza-number-stepper.is-invalid .kodza-number-stepper__box:focus-within:not(#_) {
  box-shadow: inset 0 0 0 1.5px var(--kz-number-error), 0 0 0 4px var(--kz-number-soft);
}

.kodza-number-stepper__input:not(#_) {
  display: block;
  box-sizing: border-box;
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 25px 16px 9px;
  border: 0;
  border-radius: inherit;
  background: none;
  color: inherit;
  font: inherit;
  font-size: 15px;
  line-height: 22px;
  font-variant-numeric: tabular-nums;
  outline: none;
}

.kodza-number-stepper__input:disabled:not(#_) {
  cursor: not-allowed;
}

.kodza-number-stepper.is-ready .kodza-number-stepper__input:not(#_) {
  font-size: var(--kz-number-value-size);
  font-weight: 500;
  letter-spacing: -0.01em;
  text-align: center;
}

.kodza-number-stepper.is-ready .kodza-number-stepper__input:not(#_) {
  position: relative;
  z-index: 1;
  padding: 25px var(--kz-number-side) 9px;
  color: transparent;
  caret-color: var(--kz-number-fg);
  -moz-appearance: textfield;
  appearance: textfield;
}

.kodza-number-stepper.is-ready .kodza-number-stepper__input:not(#_)::-webkit-inner-spin-button,
.kodza-number-stepper.is-ready .kodza-number-stepper__input:not(#_)::-webkit-outer-spin-button {
  margin: 0;
  -webkit-appearance: none;
  appearance: none;
}

.kodza-number-stepper.is-typing .kodza-number-stepper__input:not(#_) {
  color: inherit;
}

.kodza-number-stepper--compact .kodza-number-stepper__input:not(#_) {
  padding: 11px 16px;
}

.kodza-number-stepper--compact.is-ready .kodza-number-stepper__input:not(#_) {
  padding: 11px var(--kz-number-side);
}

.kodza-number-stepper__button:not(#_) {
  position: absolute;
  top: var(--kz-number-inset);
  z-index: 2;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  width: var(--kz-number-button-size);
  height: var(--kz-number-button-size);
  margin: 0;
  padding: 0;
  border: 0;
  border-radius: var(--kz-number-button-radius);
  background: var(--kz-number-button);
  color: var(--kz-number-fg);
  font: inherit;
  cursor: pointer;
  touch-action: manipulation;
  user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
  -webkit-tap-highlight-color: transparent;
  transition: background-color calc(0.15s * var(--kz-motion-scale, 1)) ease,
    transform calc(0.15s * var(--kz-motion-scale, 1)) var(--kz-number-ease);
}

.kodza-number-stepper__minus:not(#_) {
  left: var(--kz-number-inset);
}

.kodza-number-stepper__plus:not(#_) {
  right: var(--kz-number-inset);
}

.kodza-number-stepper__button svg:not(#_) {
  transition: opacity calc(0.2s * var(--kz-motion-scale, 1)) ease;
}

@media (hover: hover) {
  .kodza-number-stepper__button:hover:not(:disabled):not(#_) {
    background: var(--kz-number-button-hover);
  }
}

.kodza-number-stepper__button.is-pressed:not(#_) {
  background: var(--kz-number-button-press);
  transform: scale(0.92);
}

.kodza-number-stepper__button:disabled:not(#_) {
  background: transparent;
  cursor: not-allowed;
}

.kodza-number-stepper.is-disabled .kodza-number-stepper__button:not(#_) {
  opacity: 0.5;
}

.kodza-number-stepper__note:not(#_) {
  display: grid;
  margin: 0;
  padding: 0 2px;
  font-family: var(--kz-font-label, inherit);
  font-size: var(--kz-font-label-size, 13px);
  font-weight: var(--kz-font-label-weight, inherit);
  letter-spacing: var(--kz-font-label-tracking, inherit);
  line-height: var(--kz-font-label-leading, 1.4);
  text-transform: var(--kz-font-label-case, inherit);
}

@media (prefers-reduced-motion: reduce) {
  .kodza-number-stepper__box:not(#_),
  .kodza-number-stepper__button svg:not(#_) {
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
  }
}

@media (prefers-reduced-motion: reduce) {
  .kodza-number-stepper__button:not(#_) {
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
  }
}
```

```js
// Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license
// Kodza — Number Stepper
// A real number input between − and +, which the form still sends. Each digit that changes rolls
// in the direction of the count: up, the old digit leaves upward and the new one comes from
// below; down, the other way. A new place (9 to 10) opens its room as its digit rolls in.
// Holding − or + steps again and again, faster and faster; the button at the edge goes dim at
// the limit. The arrows step too (Page keys by ten, Home and End to the ends). Typing stays
// possible: out of range, the error says why, and on leaving the field the value rolls back
// into range, snapped to the step. min, max and step are read from the input.
// "change" fires on the real input at each step; after setting .value from a script, fire
// "change" on it. The words and timings are below; each word can be set per field with
// data-text-<name> (data-text-max="…"), {min}, {max}, {step}, {label} and {value} are filled in.
(() => {
  const SELECTOR = '.kodza-number-stepper';
  const WORDS = {
    max: '{max} max.', // under the field, while typing past the max
    min: '{min} min.',
    step: 'Steps of {step}.',
    number: 'Numbers only.',
    required: 'Pick a number.',
    decrease: 'Decrease', // the − button, for screen readers
    increase: 'Increase',
    live: '{label}: {value}', // read out after a press on − or +
  };
  const ROLL = 280; // ms, a digit rolling to the next one
  const HOLD = 420; // ms to hold − or + before it repeats (a wait: not scaled by the site's pace)
  const REPEAT = 160; // ms between the first repeats
  const SPEED_UP = 0.86; // each repeat comes this much sooner
  const FASTEST = 45; // ms between repeats, at full speed
  const PAGE = 10; // steps for Page Up and Page Down
  const BUMP = 3; // px, the number nudging at a limit the arrows cannot pass
  const ease = 'cubic-bezier(0.22, 1, 0.36, 1)';

  const reduceMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  // The site's pace, --kz-motion-scale (set on :root, read on the instance): every duration of the
  // script times it, and 0 moves nothing, like reduced motion
  const paceOf = (el) => {
    const pace = parseFloat(getComputedStyle(el).getPropertyValue('--kz-motion-scale'));
    return pace >= 0 ? pace : 1;
  };
  const icon = (d) => `<svg viewBox="0 0 14 14" aria-hidden="true"><path d="${d}"/></svg>`;
  const fill = (words, values) => words.replace(/\{(\w+)\}/g, (all, key) => (key in values ? values[key] : all));
  const places = (n) => (String(n).split('.')[1] || '').length;
  let uid = 0;

  // One instance. Everything it starts is tied to `signal`, so kodza:destroy stops it all
  function mount(root, signal) {
    const pace = paceOf(root);
    const still = reduceMotion || !pace; // the still path: no motion asked, by the visitor or the site
    const native = root.querySelector('.kodza-number-stepper__input');
    const box = root.querySelector('.kodza-number-stepper__box');
    const label = root.querySelector('.kodza-number-stepper__label');
    const hint = root.querySelector('.kodza-number-stepper__hint');
    const error = root.querySelector('.kodza-number-stepper__error');
    if (!native || !box) return;
    const word = (key) => root.dataset[`text${key[0].toUpperCase()}${key.slice(1)}`] || WORDS[key];
    const id = `kodza-number-stepper-${++uid}`;

    // The digits over the input, the two buttons, and what screen readers hear
    const value = document.createElement('span');
    value.className = 'kodza-number-stepper__value';
    value.setAttribute('aria-hidden', 'true');
    native.after(value);
    const button = (side, key, d) => {
      const el = document.createElement('button');
      el.type = 'button';
      el.className = `kodza-number-stepper__button kodza-number-stepper__${side}`;
      el.tabIndex = -1; // the arrows do it from the field; screen readers still reach it
      el.setAttribute('aria-label', word(key));
      el.innerHTML = icon(d);
      return el;
    };
    const minus = button('minus', 'decrease', 'M3 7h8');
    const plus = button('plus', 'increase', 'M3 7h8M7 3v8');
    box.after(minus, plus);
    const live = document.createElement('span');
    live.className = 'kodza-number-stepper__live';
    live.setAttribute('aria-live', 'polite');
    root.append(live);
    if (hint || error) {
      if (hint) hint.id = `${id}-hint`;
      if (error) error.id = `${id}-error`;
      native.setAttribute('aria-describedby', [hint?.id, error?.id].filter(Boolean).join(' '));
    }

    // min, max and step as the input has them now (a script may change them)
    const rules = () => {
      const min = parseFloat(native.min);
      const max = parseFloat(native.max);
      const any = native.step === 'any';
      const step = parseFloat(native.step) > 0 ? parseFloat(native.step) : 1;
      const base = Number.isFinite(min) ? min : 0; // the steps count from the min, as the browser does
      const decimals = any ? null : Math.max(places(step), Number.isFinite(min) ? places(min) : 0);
      const round = (n) => (decimals === null ? n : Number(n.toFixed(decimals)));
      // The highest value on a step, at or under the max
      const top = Number.isFinite(max) ? (any ? max : round(base + Math.floor((max - base) / step + 1e-9) * step)) : Infinity;
      const bottom = Number.isFinite(min) ? min : -Infinity;
      return { min, max, step, any, base, decimals, round, top, bottom };
    };
    const format = (n, r = rules()) => (r.decimals === null ? String(n) : n.toFixed(r.decimals));
    const current = () => (native.value === '' ? NaN : Number(native.value));
    // A value back on a step and inside the range
    const fit = (n, r = rules()) => {
      let next = r.any ? n : r.round(r.base + Math.round((n - r.base) / r.step) * r.step);
      next = Math.min(Math.max(next, r.bottom), r.top);
      return r.round(next);
    };

    // Hint and error share one line
    const say = (text) => {
      if (!error) return;
      error.textContent = text;
      root.classList.add('is-invalid');
      native.setAttribute('aria-invalid', 'true');
    };
    const clearError = () => {
      if (!error) return;
      root.classList.remove('is-invalid');
      native.removeAttribute('aria-invalid');
    };
    const tell = (text) => {
      live.textContent = '';
      requestAnimationFrame(() => { live.textContent = text; });
    };

    // The digits: one slot per place, lined up from the right, so 9 to 10 rolls only the units
    // and opens a new place on the left
    let shown = '';
    let slots = [];
    const slot = () => {
      const el = document.createElement('span');
      el.className = 'kodza-number-stepper__digit';
      return { el, now: null };
    };
    // A slot's digit leaves, its new one (if any) comes in, from below when the count goes up
    const swap = (place, char, dir, duration) => {
      const old = place.now;
      place.now = null;
      if (char) {
        place.now = document.createElement('span');
        place.now.textContent = char;
        place.el.append(place.now);
      }
      if (still || !duration) {
        old?.remove();
        return;
      }
      const from = dir > 0 ? 100 : -100;
      place.now?.animate([{ transform: `translateY(${from}%)` }, { transform: 'none' }], { duration, easing: ease });
      if (!old) return;
      // Still arriving from a previous step: it leaves from where it is
      const at = getComputedStyle(old).transform;
      old.getAnimations().forEach((animation) => animation.cancel());
      old.animate([{ transform: at === 'none' ? 'none' : at }, { transform: `translateY(${-from}%)` }], { duration, easing: ease, fill: 'forwards' })
        .finished.then(() => old.remove(), () => {});
    };
    const show = (text, dir = 1, duration = ROLL * pace) => {
      const before = shown.padStart(Math.max(shown.length, text.length));
      const after = text.padStart(before.length);
      shown = text;
      // Slots lined up with the longer of the two
      while (slots.length < before.length) {
        const place = slot();
        value.prepend(place.el);
        slots.unshift(place);
      }
      const keep = [];
      slots.forEach((place, i) => {
        const was = before[i] === ' ' ? '' : before[i];
        const next = after[i] === ' ' ? '' : after[i];
        if (was !== next) swap(place, next, dir, duration);
        if (next) keep.push(place);
        const opens = !was && next;
        const closes = was && !next;
        if (!opens && !closes) return;
        if (still || !duration) {
          if (closes) place.el.remove();
          return;
        }
        // A place that comes or goes: its room opens or closes as its digit rolls
        place.el.getAnimations().forEach((animation) => animation.cancel());
        const width = `${place.el.scrollWidth}px`;
        const room = place.el.animate(
          [{ width: opens ? '0px' : width }, { width: opens ? width : '0px' }],
          { duration, easing: ease, fill: closes ? 'forwards' : 'none' },
        );
        if (closes) room.finished.then(() => place.el.remove(), () => {});
      });
      slots = keep;
    };

    // Nudged at a limit the arrows cannot pass
    const bump = (dir) => {
      if (still) return;
      value.animate(
        [{ transform: 'none' }, { transform: `translateY(${-dir * BUMP}px)` }, { transform: 'none' }],
        { duration: 260 * pace, easing: 'ease-out' },
      );
    };

    // The buttons, dim at the limit
    const refresh = () => {
      const r = rules();
      const n = current();
      const off = native.disabled || native.readOnly;
      minus.disabled = off || (Number.isFinite(n) && n <= r.bottom);
      plus.disabled = off || (Number.isFinite(n) && n >= r.top);
      root.classList.toggle('is-disabled', native.disabled);
      if ((minus.disabled && holding === -1) || (plus.disabled && holding === 1)) stopHold();
    };

    let syncing = false;
    const write = (text, dir, duration) => {
      native.value = text;
      syncing = true;
      native.dispatchEvent(new Event('input', { bubbles: true }));
      native.dispatchEvent(new Event('change', { bubbles: true }));
      syncing = false;
      clearError();
      show(text, dir, duration);
      refresh();
    };

    // Typing: the input shows its own text; leaving the field (or a step) puts it in range
    let typing = false;
    const check = () => {
      const r = rules();
      const n = current();
      if (native.validity.badInput) return say(word('number'));
      if (!Number.isFinite(n)) return clearError();
      if (n > r.max) return say(fill(word('max'), { max: format(r.max, r) }));
      if (n < r.min) return say(fill(word('min'), { min: format(r.min, r) }));
      if (!r.any && Math.abs(fit(n, r) - n) > 1e-9) return say(fill(word('step'), { step: r.step }));
      clearError();
    };
    const commit = () => {
      if (!typing) return;
      typing = false;
      const typed = native.value;
      if (native.validity.badInput) {
        native.value = shown; // not a number: the last one comes back
      } else if (typed !== '') {
        const n = Number(typed);
        const next = format(fit(n));
        // The digits take over from the typed text, then roll to the value in range
        show(typed, 1, 0);
        if (next !== typed) write(next, Number(next) > n ? 1 : -1);
      } else {
        show('', 1, 0);
      }
      root.classList.remove('is-typing');
      clearError();
      refresh();
    };

    // One step (or several: Page keys), from the value there now
    const stepBy = (count, duration) => {
      commit();
      if (native.disabled || native.readOnly) return false;
      const r = rules();
      const n = current();
      let next;
      if (!Number.isFinite(n)) next = fit(r.base > r.top ? r.top : Math.max(r.base, r.bottom), r);
      else {
        const k = (n - r.base) / r.step;
        const from = count > 0 ? Math.floor(k + 1e-9) : Math.ceil(k - 1e-9);
        next = r.round(Math.min(Math.max(r.base + (from + count) * r.step, r.bottom), r.top));
      }
      if (Number.isFinite(n) && next === n) return false;
      write(format(next, r), Number.isFinite(n) && next < n ? -1 : 1, duration);
      return true;
    };
    const jump = (to) => {
      commit();
      const n = current();
      if (native.disabled || native.readOnly || !Number.isFinite(to) || to === n) return false;
      write(format(to), Number.isFinite(n) && to < n ? -1 : 1);
      return true;
    };

    // Held down: once, then again after HOLD, faster and faster
    let holding = 0;
    let timer = 0;
    let pressed = null;
    const stopHold = () => {
      clearTimeout(timer);
      if (holding && shown) tell(fill(word('live'), { label: label?.textContent.trim() || '', value: shown }));
      holding = 0;
      pressed?.classList.remove('is-pressed');
      pressed = null;
    };
    const startHold = (dir, el) => {
      stopHold();
      if (!stepBy(dir)) return;
      holding = dir;
      pressed = el;
      el.classList.add('is-pressed');
      let wait = REPEAT;
      const again = () => {
        // Fast repeats roll faster too, so each digit still lands before the next one leaves
        if (!stepBy(dir, Math.min(ROLL, wait * 1.4) * pace)) return stopHold();
        wait = Math.max(FASTEST, wait * SPEED_UP);
        timer = setTimeout(again, wait);
      };
      timer = setTimeout(again, HOLD);
    };
    [[minus, -1], [plus, 1]].forEach(([el, dir]) => {
      el.addEventListener('pointerdown', (event) => {
        if (event.button !== 0 || el.disabled) return;
        event.preventDefault(); // the focus stays where it is, nothing gets selected
        startHold(dir, el);
      }, { signal });
      el.addEventListener('pointerleave', stopHold, { signal });
      // Pressed by a screen reader or a script (no pointer): one step
      el.addEventListener('click', (event) => {
        if (event.detail !== 0) return;
        if (stepBy(dir)) tell(fill(word('live'), { label: label?.textContent.trim() || '', value: shown }));
      }, { signal });
      el.addEventListener('contextmenu', (event) => event.preventDefault(), { signal });
    });
    document.addEventListener('pointerup', stopHold, { signal });
    document.addEventListener('pointercancel', stopHold, { signal });
    window.addEventListener('blur', stopHold, { signal });

    // The keys, in the field. The matching button is pressed with them
    let keyed = null;
    const press = (el) => {
      keyed?.classList.remove('is-pressed');
      keyed = el;
      el?.classList.add('is-pressed');
    };
    native.addEventListener('keydown', (event) => {
      if (event.altKey || event.ctrlKey || event.metaKey) return;
      const r = rules();
      let dir = 0;
      let moved = false;
      if (event.key === 'ArrowUp' || event.key === 'ArrowDown') {
        dir = event.key === 'ArrowUp' ? 1 : -1;
        moved = stepBy(dir);
      } else if (event.key === 'PageUp' || event.key === 'PageDown') {
        dir = event.key === 'PageUp' ? 1 : -1;
        moved = stepBy(dir * PAGE);
      } else if ((event.key === 'Home' && Number.isFinite(r.min)) || (event.key === 'End' && Number.isFinite(r.max))) {
        dir = event.key === 'End' ? 1 : -1;
        moved = jump(dir > 0 ? r.top : r.min);
      } else if (event.key === 'Enter') {
        commit(); // a typed value in range first, then the form sends as usual
        return;
      } else return;
      event.preventDefault();
      if (native.disabled || native.readOnly) return;
      press(dir > 0 ? plus : minus);
      if (!moved) bump(dir);
    }, { signal });
    native.addEventListener('keyup', () => press(null), { signal });
    native.addEventListener('blur', () => {
      press(null);
      commit();
    }, { signal });

    native.addEventListener('input', () => {
      if (syncing) return;
      typing = true;
      root.classList.add('is-typing');
      check();
      refresh();
    }, { signal });
    // The form's own check: the error under the field instead of the browser's bubble
    native.addEventListener('invalid', (event) => {
      event.preventDefault();
      say(native.validity.valueMissing ? word('required') : native.validationMessage);
      const first = native.form && [...native.form.elements].find((el) => el.willValidate && !el.validity.valid);
      if (!native.form || first === native) native.focus();
    }, { signal });

    // A value set from outside (a script, the form's reset): the digits roll to it
    const read = () => {
      if (typing) return;
      const text = native.value;
      if (text === shown) return refresh();
      const was = Number(shown);
      show(text, Number.isFinite(was) && Number(text) < was ? -1 : 1);
      clearError();
      refresh();
    };
    native.addEventListener('change', () => {
      if (!syncing) read();
    }, { signal });
    native.form?.addEventListener('reset', () => setTimeout(() => {
      typing = false;
      root.classList.remove('is-typing');
      read();
    }), { signal });
    const observer = new MutationObserver(refresh);
    observer.observe(native, { attributes: true, attributeFilter: ['min', 'max', 'step', 'disabled', 'readonly', 'required'] });
    signal.addEventListener('abort', () => {
      observer.disconnect();
      clearTimeout(timer);
    }, { once: true });

    show(native.value, 1, 0);
    refresh();
  }

  // Kodza lifecycle, the same in every component: `kodza:init` starts the instances inside
  // event.detail.root (the whole page by default), `kodza:destroy` stops them and puts their
  // markup back. For themes and apps that swap content without a page load. Each running root
  // keeps its markup as written under KODZA, shared by every Kodza script on the page: a Kodza
  // component inside another one is saved as written, not half-started, and stopped with it. Two
  // components on one root (a reveal on a stat card) both start, and stop together.
  const KODZA = Symbol.for('kodza');
  const RUNNING = Symbol.for(`kodza ${SELECTOR}`); // a root this component runs on, for every copy of this script
  const instances = new WeakMap();
  const find = (scope = document) => [scope, ...scope.querySelectorAll(SELECTOR)].filter((el) => el.matches?.(SELECTOR));
  const attrsOf = (el) => [...el.attributes].map((a) => [a.name, a.value]);
  const put = (el, saved) => {
    [...el.attributes].forEach((a) => el.removeAttribute(a.name));
    saved.attrs.forEach(([name, value]) => el.setAttribute(name, value));
    el.innerHTML = saved.html;
  };
  // The markup inside a root as written: Kodza components already running in it give back their own
  const written = (root) => {
    const all = [...root.querySelectorAll('*')];
    if (!all.some((el) => el[KODZA])) return root.innerHTML;
    const copy = root.cloneNode(true);
    const twins = copy.querySelectorAll('*');
    let last = null;
    all.forEach((el, i) => {
      if (!el[KODZA] || last?.contains(el)) return;
      last = el;
      put(twins[i], el[KODZA]);
    });
    return copy.innerHTML;
  };
  const init = (scope) => find(scope).forEach((root) => {
    // Already running, maybe from another copy of this script. Marked is-ready with no Kodza component
    // running on it, a root is a copy of a started one (a cloned slide): it is left as it is
    if (root[RUNNING] || (root.classList.contains('is-ready') && !root[KODZA])) return;
    // Rendered by React (data-kodza-manual): React starts it, with an init aimed at that markup once
    // it has hydrated it. Any earlier start would change markup React has not taken over yet
    const owner = root.closest('[data-kodza-manual]');
    if (owner && !(scope && owner.contains(scope))) return;
    const controller = new AbortController();
    // Another Kodza component already running on this root: its markup as written is kept, and the
    // two stop together
    const before = root[KODZA];
    const saved = { html: before ? before.html : written(root), attrs: before ? before.attrs : attrsOf(root), stop: () => destroy(root) };
    if (before) before.above = saved;
    instances.set(root, { controller, saved, before });
    root[KODZA] = saved;
    root[RUNNING] = true;
    mount(root, controller.signal);
    root.classList.add('is-ready');
  });
  const destroy = (scope) => find(scope).forEach((root) => {
    const instance = instances.get(root);
    if (!instance) return;
    instances.delete(root);
    instance.saved.above?.stop(); // a Kodza component started after it on the same root stops first
    // The Kodza components running inside it stop first: once its markup is put back, their own
    // script could not find them any more
    root.querySelectorAll('*').forEach((el) => el[KODZA]?.stop());
    instance.controller.abort();
    delete root[RUNNING];
    // Started on top of another one: that one stops next, and puts the markup back
    if (instance.before) {
      delete instance.before.above;
      root[KODZA] = instance.before;
      return instance.before.stop();
    }
    delete root[KODZA];
    put(root, instance.saved);
  });
  document.addEventListener('kodza:init', (event) => init(event.detail?.root));
  document.addEventListener('kodza:destroy', (event) => destroy(event.detail?.root));
  init();
  // Loaded in <head>, the script runs before the markup exists: once more when it is parsed
  if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', () => init(), { once: true });
})();
```

Free to use, from Kodza (https://kodza.dev).