# Border Trace Card

> On hover a single line draws the card border from the exact point where the pointer came in. One way, both ways, or just the corners.

Cards · card, hover, border, svg · HTML, CSS, vanilla JS · no dependencies · updated 2026-10-16
Demo: https://kodza.dev/components/hover-gradient-card/

## Files

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

- [`kodza-hover-gradient-card.css`](https://kodza.dev/registry/hover-gradient-card/kodza-hover-gradient-card.css) · 7.8 KB
- [`kodza-hover-gradient-card.js`](https://kodza.dev/registry/hover-gradient-card/kodza-hover-gradient-card.js) · 9.1 KB
- [`kodza-hover-gradient-card.html`](https://kodza.dev/registry/hover-gradient-card/kodza-hover-gradient-card.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-hover-gradient-card.css https://kodza.dev/registry/hover-gradient-card/kodza-hover-gradient-card.css
curl -fsSL --create-dirs -o kodza/kodza-hover-gradient-card.js https://kodza.dev/registry/hover-gradient-card/kodza-hover-gradient-card.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-trace`
- Variables (set them on the root element itself: it declares its own defaults):
  - `--kz-trace-bg: #ffffff`
  - `--kz-trace-fg: #0a0a0a`
  - `--kz-trace-muted: rgba(10, 10, 10, 0.62)`
  - `--kz-trace-border: rgba(10, 10, 10, 0.1)`
  - `--kz-trace-stroke: #0a0a0a`
  - `--kz-trace-width: 1.5px`
  - `--kz-trace-radius: 16px`
  - `--kz-trace-pad: 28px`
  - `--kz-trace-duration: 0.7s`
  - `--kz-trace-ease: cubic-bezier(0.65, 0, 0.35, 1)`
- Modifiers: `.kodza-trace--both`, `.kodza-trace--corners`
- Lifecycle: `kodza:init` / `kodza:destroy` on `document`, with `{ detail: { root } }` to target a container.

## 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-trace {
    --kz-trace-bg: #161616;
    --kz-trace-fg: #f2f2f0;
    --kz-trace-muted: rgba(242, 242, 240, 0.62);
    --kz-trace-border: rgba(255, 255, 255, 0.12);
    --kz-trace-stroke: #ffffff;
  }
}
```

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

## Use it

### Plain HTML page

- CSS: `kodza/kodza-hover-gradient-card.css` next to the page (the Files commands as they are), linked in `<head>`: `<link rel="stylesheet" href="kodza/kodza-hover-gradient-card.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-hover-gradient-card.js`, loaded with `<script src="kodza/kodza-hover-gradient-card.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$/{r kodza/kodza-hover-gradient-card.css' -e 'd' -e '}' -e '/^KODZA-JS$/{r kodza/kodza-hover-gradient-card.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">`.
- 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.

### 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-hover-gradient-card', $uri . 'kodza-hover-gradient-card.css', [], filemtime($dir . 'kodza-hover-gradient-card.css'));
    wp_enqueue_script('kodza-hover-gradient-card', $uri . 'kodza-hover-gradient-card.js', [], filemtime($dir . 'kodza-hover-gradient-card.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-trace { --kz-trace-fg: var(TEXT, #0a0a0a); --kz-trace-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-hover-gradient-card.css` and `assets/kodza-hover-gradient-card.js` (the Files commands with `-o assets/…`).
- In the section: `{{ 'kodza-hover-gradient-card.css' | asset_url | stylesheet_tag }}` and `<script src="{{ 'kodza-hover-gradient-card.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/`): `BorderTraceCard.tsx` (below), the CSS block under Code saved as `hover-gradient-card.css` and the JS block as `hover-gradient-card.js`, both as they are. The HTML block is already inside the component: skip it.
- Use it: `import { BorderTraceCard } from '@/components/kodza/BorderTraceCard';` then `<BorderTraceCard />`. Props: `variant` ("both", "corners", or several in an array), `vars` (the `--kz-…` variables listed under API, e.g. `vars={{ '--kz-trace-bg': … }}`), `className`, `style` and the other props of its `<article>` (`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 './hover-gradient-card.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 — Border Trace Card, for React. From https://kodza.dev/components/hover-gradient-card/
// 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: hover-gradient-card.css and hover-gradient-card.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 './hover-gradient-card.css';

type Variant = "both" | "corners";

export type BorderTraceCardProps = Omit<ComponentPropsWithoutRef<'article'>, "children" | "variant" | "vars"> & {
  /** Modifier class(es): .kodza-trace--both, .kodza-trace--corners */
  variant?: Variant | Variant[];
  /** Settings, as CSS variables on the root */
  vars?: {
    /** default: #ffffff */
    "--kz-trace-bg"?: string | number;
    /** default: #0a0a0a */
    "--kz-trace-fg"?: string | number;
    /** default: rgba(10, 10, 10, 0.62) */
    "--kz-trace-muted"?: string | number;
    /** default: rgba(10, 10, 10, 0.1) */
    "--kz-trace-border"?: string | number;
    /** default: #0a0a0a */
    "--kz-trace-stroke"?: string | number;
    /** default: 1.5px */
    "--kz-trace-width"?: string | number;
    /** default: 16px */
    "--kz-trace-radius"?: string | number;
    /** default: 28px */
    "--kz-trace-pad"?: string | number;
    /** default: 0.7s */
    "--kz-trace-duration"?: string | number;
    /** default: cubic-bezier(0.65, 0, 0.35, 1) */
    "--kz-trace-ease"?: string | number;
  };
  className?: string;
};

export function BorderTraceCard({ variant, vars, className, style, ...rest }: BorderTraceCardProps) {
  const ref = useRef<ComponentRef<'article'>>(null);
  const classes = ["kodza-trace", ...([] as string[]).concat(variant ?? []).map((v) => `kodza-trace--${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('./hover-gradient-card.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 (
    <article key={key} {...rest} className={classes} style={{ ...vars, ...style } as CSSProperties} ref={ref}>
      <p className="kodza-trace__label">Setup</p>
      <h3 className="kodza-trace__title">Copy. Paste. Done.</h3>
      <p className="kodza-trace__text">No config files, no package hell. Just HTML, CSS and a little motion.</p>
    </article>
  );
}
```

## Code

```html
<article class="kodza-trace">
  <p class="kodza-trace__label">Setup</p>
  <h3 class="kodza-trace__title">Copy. Paste. Done.</h3>
  <p class="kodza-trace__text">No config files, no package hell. Just HTML, CSS and a little motion.</p>
</article>

<article class="kodza-trace kodza-trace--both">
  <p class="kodza-trace__label">Performance</p>
  <h3 class="kodza-trace__title">Smooth as butter</h3>
  <p class="kodza-trace__text">Sixty frames a second, even on your cousin's phone.</p>
</article>

<article class="kodza-trace kodza-trace--corners">
  <p class="kodza-trace__label">Accessibility</p>
  <h3 class="kodza-trace__title">Keyboard first</h3>
  <p class="kodza-trace__text">Focus states, labels and reduced motion. Already done for you.</p>
</article>
```

```css
/* Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license */
/* Kodza — Border Trace Card
   On hover a single line draws the border, starting from the exact point where the
   pointer came in. Variants: (default) one way around, --both (both ways, meeting on the
   far side), --corners (only the four corners, like a viewfinder).
   Everything is tuned with the --kz-trace-* variables. */
.kodza-trace {
  --kz-trace-bg: #ffffff;
  --kz-trace-fg: #0a0a0a;
  --kz-trace-muted: rgba(10, 10, 10, 0.62);
  --kz-trace-border: rgba(10, 10, 10, 0.1);
  --kz-trace-stroke: #0a0a0a;
  --kz-trace-width: 1.5px;
  --kz-trace-radius: 16px;
  --kz-trace-pad: 28px;
  --kz-trace-duration: 0.7s;
  --kz-trace-ease: cubic-bezier(0.65, 0, 0.35, 1);

  position: relative;
  display: flex;
  box-sizing: border-box;
  flex-direction: column;
  gap: 8px;
  min-height: calc(220px + 2 * var(--kz-trace-pad));
  padding: var(--kz-trace-pad);
  border-radius: var(--kz-trace-radius);
  background: var(--kz-trace-bg);
  box-shadow: inset 0 0 0 1px var(--kz-trace-border);
  color: var(--kz-trace-fg);
}

.kodza-trace__label {
  margin: 0 0 auto;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 12px;
  color: var(--kz-trace-muted);
}

.kodza-trace__title {
  margin: 0;
  font-size: 22px;
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.kodza-trace__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.55;
  color: var(--kz-trace-muted);
}

/* The traced line (drawn by the script) */
.kodza-trace__svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: visible;
  pointer-events: none;
}

.kodza-trace__svg path {
  fill: none;
  stroke: var(--kz-trace-stroke);
  stroke-width: var(--kz-trace-width);
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* Without the script, the border simply firms up */
.kodza-trace:not(.is-ready):hover {
  box-shadow: inset 0 0 0 var(--kz-trace-width) var(--kz-trace-stroke);
}

@media (prefers-reduced-motion: reduce) {
  .kodza-trace:hover {
    box-shadow: inset 0 0 0 var(--kz-trace-width) var(--kz-trace-stroke);
  }

  .kodza-trace__svg {
    display: none;
  }
}

/* Theming example — on a dark background:
.dark-section .kodza-trace {
  --kz-trace-bg: #161616;
  --kz-trace-fg: #f2f2f0;
  --kz-trace-muted: rgba(242, 242, 240, 0.62);
  --kz-trace-border: rgba(255, 255, 255, 0.12);
  --kz-trace-stroke: #ffffff;
}
*/

/* kodza-guard 8d68f1bbc6b5 — 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-trace__svg):not(#_):where(:not([hidden])) {
  display: revert;
}

:where(.kodza-trace__svg):not(#_):where([hidden]) {
  display: none;
}

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

.kodza-trace:not(#_) {
  border: revert;
  outline: revert;
  text-decoration: revert;
  transition: revert;
  list-style: revert;
  outline-offset: revert;
  appearance: revert;
  max-height: 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-trace__label:not(#_) {
  border: 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;
  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-trace__title:not(#_) {
  border: 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-style: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-trace__text:not(#_) {
  border: 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;
  font-family: revert;
  font-weight: revert;
  font-style: revert;
  letter-spacing: revert;
  text-transform: revert;
  text-underline-offset: revert;
  text-align: revert;
  text-indent: revert;
  text-shadow: revert;
  vertical-align: revert;
}

.kodza-trace__svg: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;
  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-trace__label:not(#_):where(:not([hidden])),
.kodza-trace__title:not(#_):where(:not([hidden])),
.kodza-trace__text:not(#_):where(:not([hidden])) {
  display: revert;
}

.kodza-trace__label:not(#_):where([hidden]),
.kodza-trace__title:not(#_):where([hidden]),
.kodza-trace__text: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-trace:not(#_) {
  position: relative;
  display: flex;
  box-sizing: border-box;
  padding: var(--kz-trace-pad);
  border-radius: var(--kz-trace-radius);
  background: var(--kz-trace-bg);
  box-shadow: inset 0 0 0 1px var(--kz-trace-border);
  color: var(--kz-trace-fg);
}

.kodza-trace__label:not(#_) {
  margin: 0 0 auto;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 12px;
  color: var(--kz-trace-muted);
}

.kodza-trace__title:not(#_) {
  margin: 0;
  font-size: 22px;
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.kodza-trace__text:not(#_) {
  margin: 0;
  font-size: 15px;
  line-height: 1.55;
  color: var(--kz-trace-muted);
}

.kodza-trace__svg:not(#_) {
  position: absolute;
}

.kodza-trace:not(.is-ready):hover:not(#_) {
  box-shadow: inset 0 0 0 var(--kz-trace-width) var(--kz-trace-stroke);
}

@media (prefers-reduced-motion: reduce) {
  .kodza-trace:hover:not(#_) {
    box-shadow: inset 0 0 0 var(--kz-trace-width) var(--kz-trace-stroke);
  }
}

@media (prefers-reduced-motion: reduce) {
  .kodza-trace__svg:not(#_) {
    display: none;
  }
}
```

```js
// Kodza License: free to use, client work included. Not to resell or redistribute, ported or not: https://kodza.dev/docs/#print-license
// Kodza — Border Trace Card
// Draws the card's rounded border as an SVG path, then animates its dash from the point
// of the border closest to where the pointer entered. The path goes around three times,
// so a dash can start anywhere and still be one continuous line.
(() => {
  const SELECTOR = '.kodza-trace';
  if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) return;
  const SVG = 'http://www.w3.org/2000/svg';
  const CORNER = 26; // length of each corner arm, for --corners

  // A rounded rectangle, starting at the top-left, going clockwise (only the drawing commands)
  function lap(w, h, r, i) {
    const x0 = i, y0 = i, x1 = w - i, y1 = h - i;
    r = Math.max(0, Math.min(r - i, (x1 - x0) / 2, (y1 - y0) / 2));
    return `H ${x1 - r} A ${r} ${r} 0 0 1 ${x1} ${y0 + r} V ${y1 - r} A ${r} ${r} 0 0 1 ${x1 - r} ${y1} ` +
      `H ${x0 + r} A ${r} ${r} 0 0 1 ${x0} ${y1 - r} V ${y0 + r} A ${r} ${r} 0 0 1 ${x0 + r} ${y0}`;
  }

  // Four corner brackets, each drawn from one arm to the other
  function corners(w, h, r, i) {
    const x0 = i, y0 = i, x1 = w - i, y1 = h - i, c = CORNER;
    r = Math.max(0, r - i);
    return [
      `M ${x0} ${y0 + r + c} V ${y0 + r} A ${r} ${r} 0 0 1 ${x0 + r} ${y0} H ${x0 + r + c}`,
      `M ${x1 - r - c} ${y0} H ${x1 - r} A ${r} ${r} 0 0 1 ${x1} ${y0 + r} V ${y0 + r + c}`,
      `M ${x1} ${y1 - r - c} V ${y1 - r} A ${r} ${r} 0 0 1 ${x1 - r} ${y1} H ${x1 - r - c}`,
      `M ${x0 + r + c} ${y1} H ${x0 + r} A ${r} ${r} 0 0 1 ${x0} ${y1 - r} V ${y1 - r - c}`,
    ];
  }

  // One instance. Everything it starts is tied to `signal`, so kodza:destroy stops it all
  function mount(card, signal) {
    const mode = card.classList.contains('kodza-trace--corners') ? 'corners' : card.classList.contains('kodza-trace--both') ? 'both' : 'one';
    const svg = document.createElementNS(SVG, 'svg');
    svg.setAttribute('class', 'kodza-trace__svg');
    svg.setAttribute('aria-hidden', 'true');
    card.append(svg);

    const style = getComputedStyle(card);
    const duration = parseFloat(style.getPropertyValue('--kz-trace-duration')) * 1000 || 700;
    const ease = style.getPropertyValue('--kz-trace-ease').trim() || 'ease';
    let paths = [];
    let lapLength = 0;
    let samples = [];
    let entry = 0;

    function build() {
      const { width: w, height: h } = card.getBoundingClientRect();
      const r = parseFloat(style.getPropertyValue('--kz-trace-radius')) || 0;
      const inset = (parseFloat(style.getPropertyValue('--kz-trace-width')) || 1.5) / 2;
      svg.setAttribute('viewBox', `0 0 ${w} ${h}`);
      svg.replaceChildren();
      const shapes = mode === 'corners' ? corners(w, h, r, inset) : [`M ${inset + Math.max(0, r - inset)} ${inset} ` + lap(w, h, r, inset).repeat(1) + ' ' + lap(w, h, r, inset) + ' ' + lap(w, h, r, inset)];
      paths = shapes.map((d) => {
        const path = document.createElementNS(SVG, 'path');
        path.setAttribute('d', d);
        // At rest the dash is zero-long, and a round cap would still draw a dot: hidden until traced
        path.style.opacity = 0;
        svg.append(path);
        return path;
      });
      if (mode === 'corners') {
        paths.forEach((p) => {
          p.setAttribute('pathLength', '1');
          p.style.strokeDasharray = '0 1';
        });
        return;
      }
      lapLength = paths[0].getTotalLength() / 3;
      paths[0].style.strokeDasharray = `0 ${lapLength * 3}`;
      // Points along one lap, to find where the pointer came in
      samples = Array.from({ length: 240 }, (_, k) => {
        const s = (k / 240) * lapLength;
        const p = paths[0].getPointAtLength(s);
        return { s, x: p.x, y: p.y };
      });
    }

    const nearest = (x, y) => samples.reduce((best, p) => ((p.x - x) ** 2 + (p.y - y) ** 2 < (best.x - x) ** 2 + (best.y - y) ** 2 ? p : best)).s;

    function enter(event) {
      const rect = card.getBoundingClientRect();
      const L = lapLength;
      if (mode === 'corners') {
        // The corner closest to the pointer goes first, then the others
        const cx = event ? event.clientX - rect.left : rect.width / 2;
        const cy = event ? event.clientY - rect.top : 0;
        const order = [[0, 0], [rect.width, 0], [rect.width, rect.height], [0, rect.height]]
          .map(([x, y], i) => ({ i, d: (x - cx) ** 2 + (y - cy) ** 2 }))
          .sort((a, b) => a.d - b.d);
        order.forEach(({ i }, rank) => {
          paths[i].getAnimations().forEach((a) => a.cancel());
          // Each corner shows up when its own line starts, not during its delay (a dot would wait there)
          paths[i].animate([
            { strokeDasharray: '0 1', opacity: 0 },
            { strokeDasharray: '0 1', opacity: 1, offset: 0.01 },
            { strokeDasharray: '1 0', opacity: 1 },
          ], { duration: duration * 0.55, delay: rank * 70, easing: ease, fill: 'both' });
        });
        return;
      }
      entry = event ? nearest(event.clientX - rect.left, event.clientY - rect.top) : 0;
      const path = paths[0];
      path.getAnimations().forEach((a) => a.cancel());
      path.style.opacity = 1;
      if (mode === 'both') {
        // One dash centred on the entry point, growing both ways until it closes the loop
        path.animate([
          { strokeDasharray: `0 ${3 * L}`, strokeDashoffset: -(entry + L) },
          { strokeDasharray: `${L} ${3 * L}`, strokeDashoffset: -(entry + L / 2) },
        ], { duration, easing: ease, fill: 'forwards' });
      } else {
        path.animate([
          { strokeDasharray: `0 ${3 * L}`, strokeDashoffset: -entry },
          { strokeDasharray: `${L} ${3 * L}`, strokeDashoffset: -entry },
        ], { duration, easing: ease, fill: 'forwards' });
      }
    }

    // Once a line has shrunk back to nothing, it hides again (a new hover cancels this first)
    const hideAfter = (path, animation) => animation.finished.then(() => {
      if (signal.aborted) return;
      path.style.opacity = 0;
      animation.cancel();
    }).catch(() => {});

    function leave() {
      const L = lapLength;
      if (mode === 'corners') {
        paths.forEach((p) => {
          p.getAnimations().forEach((a) => a.cancel());
          hideAfter(p, p.animate([{ strokeDasharray: '1 0', opacity: 1 }, { strokeDasharray: '0 1', opacity: 1 }], { duration: duration * 0.45, easing: ease, fill: 'forwards' }));
        });
        return;
      }
      const path = paths[0];
      path.getAnimations().forEach((a) => a.cancel());
      if (mode === 'both') {
        path.animate([{ opacity: 1, strokeDasharray: `${L} ${3 * L}`, strokeDashoffset: -(entry + L / 2) }, { opacity: 0, strokeDasharray: `${L} ${3 * L}`, strokeDashoffset: -(entry + L / 2) }], { duration: duration * 0.5, easing: 'ease', fill: 'forwards' });
      } else {
        // The line does not rewind: its tail catches up with its head, one lap later
        hideAfter(path, path.animate([
          { strokeDasharray: `${L} ${3 * L}`, strokeDashoffset: -entry },
          { strokeDasharray: `0 ${3 * L}`, strokeDashoffset: -(entry + L) },
        ], { duration, easing: ease, fill: 'forwards' }));
      }
    }

    build();
    const observer = new ResizeObserver(build);
    observer.observe(card);
    signal.addEventListener('abort', () => observer.disconnect());
    card.addEventListener('pointerenter', enter, { signal });
    card.addEventListener('pointerleave', leave, { signal });
    card.addEventListener('focusin', () => enter(null), { signal });
    card.addEventListener('focusout', leave, { signal });
  }

  // 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).