# Ring to fill checkbox

> A round outline thickens inwards until it becomes a solid dot, and a small tick pops up inside.

- Category: [Checkboxes](https://library.aimran.es/components/checkboxes)
- Built with: HTML + CSS
- Live editor: https://library.aimran.es/blocks/uv-ck2-morph
- Library: AIMRAN Library (https://library.aimran.es), free, no sign-up, by Aimran Oukham

## Where to use it

The ring closing in on itself feels soft and rounded, which fits friendly opt-ins: “Subscribe to the newsletter” at the end of a checkout, “Send me a reminder” on an event page or joining a waiting list. This round checkbox in CSS has no sharp corners at all, so it blends into playful, rounded interfaces.

Round checkboxes can be mistaken for radio buttons. Avoid mixing this one with radios in the same form, and keep the label clear so people know they can pick more than one.

## Code

### HTML

```html
<label class="uv-ck2m"><input type="checkbox"><span class="bx"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="3" stroke-linecap="round" stroke-linejoin="round"><path d="M5 12.5l4.5 4.5L19 7.5" pathLength="1"/></svg></span>Subscribe me</label>
```

### CSS

```css
.uv-ck2m {
  --c1: #0071e3;
  --c2: #8ec5ff;
  --s: 16px;
  /* tamaño */
  --k: 1;
  /* velocidad */
  --fg: #1d1d1f;
  /* texto */
  --bg: #f5f5f7;
  /* fondo */
}

.uv-ck2m {
  font-family: -apple-system,BlinkMacSystemFont,"SF Pro Text","Inter",system-ui,sans-serif;
  font-size: var(--s);
  color: var(--fg);
  -webkit-tap-highlight-color: transparent;
  display: inline-flex;
  align-items: center;
  gap: .7em;
  cursor: pointer;
  user-select: none;
  font-weight: 500;
}

.uv-ck2m input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
  pointer-events: none;
}

.uv-ck2m .bx {
  display: grid;
  place-items: center;
  width: 1.5em;
  height: 1.5em;
  border-radius: 50%;
  box-shadow: inset 0 0 0 .1em color-mix(in srgb,var(--fg) 24%,transparent);
  transition: box-shadow calc(0.42s / var(--k)) cubic-bezier(.34,1.56,.64,1),background calc(0.3s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-ck2m svg {
  width: .9em;
  height: .9em;
  color: #fff;
  scale: .4;
  opacity: 0;
  transition: scale calc(0.4s / var(--k)) cubic-bezier(.34,1.56,.64,1) calc(0.1s / var(--k)),opacity calc(0.25s / var(--k)) cubic-bezier(.25,.1,.25,1) calc(0.1s / var(--k));
}

.uv-ck2m:hover .bx {
  box-shadow: inset 0 0 0 .1em var(--c1);
}

.uv-ck2m input:checked + .bx {
  background: var(--c1);
  box-shadow: inset 0 0 0 .8em var(--c1);
}

.uv-ck2m input:checked + .bx svg {
  scale: 1;
  opacity: 1;
}
```

### React

```tsx
import type { CSSProperties } from "react";

const css = `
.uv-ck2m {
  font-family: -apple-system,BlinkMacSystemFont,"SF Pro Text","Inter",system-ui,sans-serif;
  font-size: var(--s);
  color: var(--fg);
  -webkit-tap-highlight-color: transparent;
  display: inline-flex;
  align-items: center;
  gap: .7em;
  cursor: pointer;
  user-select: none;
  font-weight: 500;
}

.uv-ck2m input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
  pointer-events: none;
}

.uv-ck2m .bx {
  display: grid;
  place-items: center;
  width: 1.5em;
  height: 1.5em;
  border-radius: 50%;
  box-shadow: inset 0 0 0 .1em color-mix(in srgb,var(--fg) 24%,transparent);
  transition: box-shadow calc(0.42s / var(--k)) cubic-bezier(.34,1.56,.64,1),background calc(0.3s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-ck2m svg {
  width: .9em;
  height: .9em;
  color: #fff;
  scale: .4;
  opacity: 0;
  transition: scale calc(0.4s / var(--k)) cubic-bezier(.34,1.56,.64,1) calc(0.1s / var(--k)),opacity calc(0.25s / var(--k)) cubic-bezier(.25,.1,.25,1) calc(0.1s / var(--k));
}

.uv-ck2m:hover .bx {
  box-shadow: inset 0 0 0 .1em var(--c1);
}

.uv-ck2m input:checked + .bx {
  background: var(--c1);
  box-shadow: inset 0 0 0 .8em var(--c1);
}

.uv-ck2m input:checked + .bx svg {
  scale: 1;
  opacity: 1;
}
`;

export default function Ck2Morph() {
  return (
    <>
      <style>{css}</style>
      <div
        style={{
          "--c1": "#0071e3",
          "--c2": "#8ec5ff",
          "--s": "16px",
          "--k": "1",
          "--fg": "#1d1d1f",
          "--bg": "#f5f5f7",
        } as CSSProperties}
      >
        <label className="uv-ck2m"><input type="checkbox" /><span className="bx"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="3" strokeLinecap="round" strokeLinejoin="round"><path d="M5 12.5l4.5 4.5L19 7.5" pathLength="1" /></svg></span>Subscribe me</label>
      </div>
    </>
  );
}
```

## Prompt for AI assistants

Paste this into ChatGPT, Claude, Cursor, v0 or Lovable to adapt the block to your stack (Tailwind, Vue, Svelte…):

````text
I want to add the “Ring to fill checkbox” block (Checkboxes) from AIMRAN Library to my project.

## What it is
A round outline thickens inwards until it becomes a solid dot, and a small tick pops up inside.

## Chosen settings
- Main color: #0071e3
- Secondary color: #8ec5ff
- Size: 16px (from 12 to 24px)
- Speed: 1x (from 0.5 to 2x)
- Text: "Subscribe me"

## What I need
1. Add it to my project with the same look and animation as the reference code: same sizes, colours, radii, shadows, timings and easing.
2. It is built with plain HTML and CSS (the reference wraps it in a React component with its CSS). If my project uses something else (Vue, Svelte, Astro, plain HTML…), translate it without losing any behaviour. If I use Tailwind, turn the styles into classes; if not, keep the CSS in its own file.
3. Expose the settings above as props (or CSS variables) with those values as defaults.
4. Make it work well on phones: nothing that depends only on hover, touch targets of at least 44 px and no overflow on 320 px screens.
5. Make it look right in light and dark mode.
6. Keep it accessible: semantic HTML, roles and aria-* where needed, visible focus and keyboard support.
7. Respect prefers-reduced-motion: with reduced motion, no big animations but the same end result.

## Reference code
```tsx
import type { CSSProperties } from "react";

const css = `
.uv-ck2m {
  font-family: -apple-system,BlinkMacSystemFont,"SF Pro Text","Inter",system-ui,sans-serif;
  font-size: var(--s);
  color: var(--fg);
  -webkit-tap-highlight-color: transparent;
  display: inline-flex;
  align-items: center;
  gap: .7em;
  cursor: pointer;
  user-select: none;
  font-weight: 500;
}

.uv-ck2m input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
  pointer-events: none;
}

.uv-ck2m .bx {
  display: grid;
  place-items: center;
  width: 1.5em;
  height: 1.5em;
  border-radius: 50%;
  box-shadow: inset 0 0 0 .1em color-mix(in srgb,var(--fg) 24%,transparent);
  transition: box-shadow calc(0.42s / var(--k)) cubic-bezier(.34,1.56,.64,1),background calc(0.3s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-ck2m svg {
  width: .9em;
  height: .9em;
  color: #fff;
  scale: .4;
  opacity: 0;
  transition: scale calc(0.4s / var(--k)) cubic-bezier(.34,1.56,.64,1) calc(0.1s / var(--k)),opacity calc(0.25s / var(--k)) cubic-bezier(.25,.1,.25,1) calc(0.1s / var(--k));
}

.uv-ck2m:hover .bx {
  box-shadow: inset 0 0 0 .1em var(--c1);
}

.uv-ck2m input:checked + .bx {
  background: var(--c1);
  box-shadow: inset 0 0 0 .8em var(--c1);
}

.uv-ck2m input:checked + .bx svg {
  scale: 1;
  opacity: 1;
}
`;

export default function Ck2Morph() {
  return (
    <>
      <style>{css}</style>
      <div
        style={{
          "--c1": "#0071e3",
          "--c2": "#8ec5ff",
          "--s": "16px",
          "--k": "1",
          "--fg": "#1d1d1f",
          "--bg": "#f5f5f7",
        } as CSSProperties}
      >
        <label className="uv-ck2m"><input type="checkbox" /><span className="bx"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="3" strokeLinecap="round" strokeLinejoin="round"><path d="M5 12.5l4.5 4.5L19 7.5" pathLength="1" /></svg></span>Subscribe me</label>
      </div>
    </>
  );
}
```

Give me the complete final code, ready to paste, and tell me in one line where to put it in my project.
````