# Before / After

> Two pictures in one frame and a handle between them: drag it, click and it glides, or use the arrow keys. It nudges once when first seen; the labels step aside.

Media · compare, slider, image, dark mode · HTML, CSS, vanilla JS · no dependencies · updated 2026-10-16
Demo: https://kodza.dev/components/before-after/

## Files

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

- [`kodza-before-after.css`](https://kodza.dev/registry/before-after/kodza-before-after.css) · 7.6 KB
- [`kodza-before-after.js`](https://kodza.dev/registry/before-after/kodza-before-after.js) · 4.4 KB
- [`kodza-before-after.html`](https://kodza.dev/registry/before-after/kodza-before-after.html) · 0.7 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-before-after.css https://kodza.dev/registry/before-after/kodza-before-after.css
curl -fsSL --create-dirs -o kodza/kodza-before-after.js https://kodza.dev/registry/before-after/kodza-before-after.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-compare`
- Variables (set them on the root element itself: it declares its own defaults):
  - `--kz-compare-line: #ffffff`
  - `--kz-compare-grip-bg: #ffffff`
  - `--kz-compare-grip-fg: #0a0a0a`
  - `--kz-compare-radius: 16px`
- 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.

- On the slider (focus in `.kodza-compare__range`):
  - `ArrowRight` / `ArrowUp`: Slides the divider right by 1%
  - `ArrowLeft` / `ArrowDown`: Slides the divider left by 1%
  - `PageUp` / `PageDown`: Slides it 10% right or left
  - `Home` / `End`: Jumps to the far left or the far right

## Dark mode

Nothing to set: it takes its colours from the text around it, or looks the same on a light and a dark page.

Its images have dark versions next to them (`kz-columns-1400.webp` → `kz-columns-dark-1400.webp`). To swap them on a dark page: `<picture><source media="(prefers-color-scheme: dark)" srcset="…-dark-….webp"><img …></picture>`.

## Use it

### Plain HTML page

- CSS: `kodza/kodza-before-after.css` next to the page (the Files commands as they are), linked in `<head>`: `<link rel="stylesheet" href="kodza/kodza-before-after.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-before-after.js`, loaded with `<script src="kodza/kodza-before-after.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. 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">`.
- 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$/{r kodza/kodza-before-after.css' -e 'd' -e '}' -e '/^KODZA-JS$/{r kodza/kodza-before-after.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">`.
- Images: the artifact blocks every other host, `kodza.dev` included, without an error. Embed each one as a `data:` URI, with a command if you can run one (`curl -s <url> | base64`; the 1400 px files weigh 10 to 30 KB), never by typing base64 out. If you can't run commands, keep the `<img>` with its `width` and `height`, and tell the user the picture stays blank inside the artifact.
- 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-before-after', $uri . 'kodza-before-after.css', [], filemtime($dir . 'kodza-before-after.css'));
    wp_enqueue_script('kodza-before-after', $uri . 'kodza-before-after.js', [], filemtime($dir . 'kodza-before-after.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: it takes the colour of the text around it (or keeps its own monochrome): nothing to point at the theme.
- 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-before-after.css` and `assets/kodza-before-after.js` (the Files commands with `-o assets/…`).
- In the section: `{{ 'kodza-before-after.css' | asset_url | stylesheet_tag }}` and `<script src="{{ 'kodza-before-after.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/`): `BeforeAfter.tsx` (below), the CSS block under Code saved as `before-after.css` and the JS block as `before-after.js`, both as they are. The HTML block is already inside the component: skip it.
- Use it: `import { BeforeAfter } from '@/components/kodza/BeforeAfter';` then `<BeforeAfter />`. Props: `vars` (the `--kz-…` variables listed under API, e.g. `vars={{ '--kz-compare-line': … }}`), `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 './before-after.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.

```tsx
'use client';
// Kodza — Before / After, for React. From https://kodza.dev/components/before-after/
// 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: before-after.css and before-after.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.
import { useRef, useEffect, type ComponentPropsWithoutRef, type ComponentRef, type CSSProperties } from 'react';
import './before-after.css';

export type BeforeAfterProps = Omit<ComponentPropsWithoutRef<'div'>, "children" | "vars"> & {
  /** Settings, as CSS variables on the root */
  vars?: {
    /** default: #ffffff */
    "--kz-compare-line"?: string | number;
    /** default: #ffffff */
    "--kz-compare-grip-bg"?: string | number;
    /** default: #0a0a0a */
    "--kz-compare-grip-fg"?: string | number;
    /** default: 16px */
    "--kz-compare-radius"?: string | number;
  };
  className?: string;
};

export function BeforeAfter({ vars, className, style, ...rest }: BeforeAfterProps) {
  const ref = useRef<ComponentRef<'div'>>(null);
  const classes = ["kodza-compare", 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('./before-after.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} style={{ ...vars, ...style } as CSSProperties} ref={ref}>
      <img className="kodza-compare__before" src="https://kodza.dev/media/kz-columns-1400.webp" alt="The columns in daylight" width="1120" height="1400" />
      <div className="kodza-compare__after">
        <img src="https://kodza.dev/media/kz-columns-dark-1400.webp" alt="The same columns in dark mode" width="1120" height="1400" />
      </div>
      <span className="kodza-compare__tag">Light</span>
      {' '}
      <span className="kodza-compare__tag kodza-compare__tag--after">Dark</span>
      {' '}
      <span className="kodza-compare__handle" aria-hidden="true">
        <svg viewBox="0 0 24 24">
          <path d="M9 7l-5 5 5 5M15 7l5 5-5 5" />
        </svg>
      </span>
      {' '}
      <input className="kodza-compare__range" type="range" min="0" max="100" defaultValue="50" step="1" aria-label="How much of the dark version to show" />
    </div>
  );
}
```

## Code

```html
<div class="kodza-compare">
  <img class="kodza-compare__before" src="https://kodza.dev/media/kz-columns-1400.webp" alt="The columns in daylight" width="1120" height="1400" />
  <div class="kodza-compare__after"><img src="https://kodza.dev/media/kz-columns-dark-1400.webp" alt="The same columns in dark mode" width="1120" height="1400" /></div>
  <span class="kodza-compare__tag">Light</span>
  <span class="kodza-compare__tag kodza-compare__tag--after">Dark</span>
  <span class="kodza-compare__handle" aria-hidden="true"><svg viewBox="0 0 24 24"><path d="M9 7l-5 5 5 5M15 7l5 5-5 5" /></svg></span>
  <input class="kodza-compare__range" type="range" min="0" max="100" value="50" step="1" aria-label="How much of the dark version to show" />
</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 — Before / After
   Two pictures in one frame and a handle between them. Drag it (mouse or finger), click
   somewhere and it glides there, or use the arrow keys: a real range input is underneath.
   The first time it is seen, it nudges once to show it moves. The labels step aside when the
   handle comes close. Everything is tuned with the --kz-compare-* variables.
   Set the start with the input's value (0 to 100), the shape with --kz-compare-ratio. */
.kodza-compare {
  --kz-compare-line: #ffffff;
  --kz-compare-grip-bg: #ffffff;
  --kz-compare-grip-fg: #0a0a0a;
  --kz-compare-radius: 16px;
  --kz-compare-pos: 50%;

  position: relative;
  display: block;
  aspect-ratio: var(--kz-compare-ratio, 4 / 3);
  overflow: hidden;
  border-radius: var(--kz-compare-radius);
  cursor: ew-resize;
  touch-action: pan-y;
  user-select: none;
  -webkit-user-select: none;
}

.kodza-compare img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  pointer-events: none;
}

.kodza-compare__after {
  position: absolute;
  inset: 0;
  clip-path: inset(0 0 0 var(--kz-compare-pos));
}

/* The handle: a line across the picture and a round grip */
.kodza-compare__handle {
  position: absolute;
  top: 0;
  bottom: 0;
  left: var(--kz-compare-pos);
  width: 2px;
  margin-left: -1px;
  background: var(--kz-compare-line);
  box-shadow: 0 0 12px rgba(0, 0, 0, 0.18);
  pointer-events: none;
}

.kodza-compare__handle svg {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 44px;
  height: 44px;
  padding: 11px;
  box-sizing: border-box;
  border-radius: 50%;
  background: var(--kz-compare-grip-bg);
  box-shadow: 0 6px 18px -6px rgba(0, 0, 0, 0.45);
  fill: none;
  stroke: var(--kz-compare-grip-fg);
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
  transform: translate(-50%, -50%);
  transition: transform 0.35s cubic-bezier(0.22, 1, 0.36, 1);
}

.kodza-compare.is-dragging .kodza-compare__handle svg {
  transform: translate(-50%, -50%) scale(0.9);
}

.kodza-compare:has(.kodza-compare__range:focus-visible) .kodza-compare__handle svg {
  outline: 2px solid var(--kz-compare-line);
  outline-offset: 3px;
}

/* The labels, which step aside when the handle comes close */
.kodza-compare__tag {
  position: absolute;
  top: 14px;
  left: 14px;
  padding: 5px 10px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.86);
  color: #0a0a0a;
  font-family: "Geist Mono", ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 11px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  pointer-events: none;
  transition: opacity 0.3s ease, transform 0.45s cubic-bezier(0.22, 1, 0.36, 1);
}

.kodza-compare__tag--after {
  right: 14px;
  left: auto;
  background: rgba(10, 10, 10, 0.78);
  color: #ffffff;
}

.kodza-compare.is-near-start .kodza-compare__tag:not(.kodza-compare__tag--after) {
  opacity: 0;
  transform: translateX(-8px);
}

.kodza-compare.is-near-end .kodza-compare__tag--after {
  opacity: 0;
  transform: translateX(8px);
}

/* The range input: invisible, but there for the keyboard and screen readers */
.kodza-compare__range {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  opacity: 0;
  pointer-events: none;
}

@media (prefers-reduced-motion: reduce) {
  .kodza-compare__handle svg,
  .kodza-compare__tag {
    transition-duration: 0.01ms !important;
  }
}

/* kodza-guard 96c5cbd32914 — 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-compare__handle svg:where(:not([class*="kodza-"]))):not(#_) {
  outline: revert;
  outline-offset: revert;
}

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

.kodza-compare:not(#_),
.kodza-compare__after:not(#_),
.kodza-compare__tag:not(#_),
.kodza-compare__handle:not(#_) {
  box-sizing: revert;
}

.kodza-compare__before:not(#_),
.kodza-compare__after img:where(:not([class*="kodza-"])):not(#_) {
  border: revert;
  margin: revert;
  padding: revert;
  border-radius: revert;
  outline: revert;
  text-decoration: revert;
  transition: 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-compare__range:not(#_) {
  border: revert;
  padding: 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-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;
  white-space: revert;
  min-height: revert;
}

.kodza-compare__handle svg:where(:not([class*="kodza-"])):not(#_) {
  border: revert;
  margin: revert;
  text-decoration: revert;
  list-style: revert;
  float: 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-compare__range:not(#_):where(:not([hidden])),
.kodza-compare__handle svg:where(:not([class*="kodza-"])):not(#_):where(:not([hidden])) {
  display: revert;
}

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

/* 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-compare img:not(#_) {
  display: block;
}

.kodza-compare__handle svg:not(#_) {
  position: absolute;
  padding: 11px;
  box-sizing: border-box;
  border-radius: 50%;
  background: var(--kz-compare-grip-bg);
  box-shadow: 0 6px 18px -6px rgba(0, 0, 0, 0.45);
  transition: transform 0.35s cubic-bezier(0.22, 1, 0.36, 1);
}

.kodza-compare:has(.kodza-compare__range:focus-visible) .kodza-compare__handle svg:not(#_) {
  outline: 2px solid var(--kz-compare-line);
  outline-offset: 3px;
}

.kodza-compare__range:not(#_) {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  opacity: 0;
  pointer-events: none;
}

@media (prefers-reduced-motion: reduce) {
  .kodza-compare__handle svg:not(#_) {
    transition-duration: 0.01ms !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 — Before / After
// Moves the handle with the pointer (exactly under it while dragging, gliding there after a
// click), with the arrow keys through the range input, and nudges once when first seen.
// Positions are read in the frame's own pixels, so a scaled parent is fine.
(() => {
  const SELECTOR = '.kodza-compare';
  const reduceMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  // One instance. Everything it starts is tied to `signal`, so kodza:destroy stops it all
  function mount(root, signal) {
    const range = root.querySelector('.kodza-compare__range');
    let pos = parseFloat(range?.value) || 50;
    let target = pos;
    let frame = 0;
    let dragging = false;

    const paint = () => {
      root.style.setProperty('--kz-compare-pos', `${pos}%`);
      root.classList.toggle('is-near-start', pos < 22);
      root.classList.toggle('is-near-end', pos > 78);
      if (range) range.value = Math.round(pos);
    };
    const glide = () => {
      if (signal.aborted) return;
      pos += (target - pos) * (dragging || reduceMotion ? 1 : 0.2);
      if (Math.abs(target - pos) < 0.05) pos = target;
      paint();
      frame = pos === target ? 0 : requestAnimationFrame(glide);
    };
    const go = (value) => {
      target = Math.min(100, Math.max(0, value));
      if (!frame) frame = requestAnimationFrame(glide);
    };
    const at = (event) => {
      const box = root.getBoundingClientRect();
      return ((event.clientX - box.left) / box.width) * 100;
    };

    root.addEventListener('pointerdown', (event) => {
      if (event.button !== 0) return;
      root.setPointerCapture(event.pointerId);
      root.classList.add('is-dragging');
      go(at(event));
    }, { signal });
    root.addEventListener('pointermove', (event) => {
      if (!root.hasPointerCapture(event.pointerId)) return;
      dragging = true;
      go(at(event));
    }, { signal });
    const release = () => {
      dragging = false;
      root.classList.remove('is-dragging');
    };
    root.addEventListener('pointerup', release, { signal });
    root.addEventListener('pointercancel', release, { signal });
    range?.addEventListener('input', () => go(parseFloat(range.value)), { signal });

    // The first time it is seen: a small nudge, to say it moves
    if (!reduceMotion && 'IntersectionObserver' in window) {
      const io = new IntersectionObserver(([entry]) => {
        if (!entry.isIntersecting) return;
        io.disconnect();
        const start = pos;
        [[start + 9, 450], [start - 6, 950], [start, 1400]].forEach(([value, delay]) => setTimeout(() => !dragging && go(value), delay));
      }, { threshold: 0.6 });
      io.observe(root);
      signal.addEventListener('abort', () => io.disconnect());
    }

    paint();
  }

  // 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.
  const instances = new WeakMap();
  const find = (scope = document) => [scope, ...scope.querySelectorAll(SELECTOR)].filter((el) => el.matches?.(SELECTOR));
  const init = (scope) => find(scope).forEach((root) => {
    if (root.classList.contains('is-ready')) return; // already running, maybe from another copy of this script
    const controller = new AbortController();
    instances.set(root, { controller, html: root.innerHTML, attrs: [...root.attributes].map((a) => [a.name, a.value]) });
    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.controller.abort();
    [...root.attributes].forEach((a) => root.removeAttribute(a.name));
    instance.attrs.forEach(([name, value]) => root.setAttribute(name, value));
    root.innerHTML = instance.html;
  });
  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).