# Outline fill button

> An outlined button that fills with color from left to right when the cursor moves over it.

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

## Where to use it

An outline button that fills on hover is the natural choice for secondary actions: “Download the PDF” on a portfolio, “Subscribe” in a blog footer or “View menu” next to a bolder “Book a table”. At rest it stays light and discreet. The fill slides in from the left and the text turns white as it goes.

Pair it with a solid button of the same color and you get a clear primary and secondary pair without extra design work. A slightly slower speed makes the fill feel more deliberate, which suits calmer brands.

## Code

### HTML

```html
<button class="uv-fill">Subscribe</button>
```

### CSS

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

.uv-fill {
  font-family: -apple-system,BlinkMacSystemFont,"SF Pro Text","Inter",system-ui,sans-serif;
  font-size: var(--s);
  font-weight: 600;
  line-height: 1;
  padding: 1em 2em;
  border: 0;
  border-radius: 999px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  position: relative;
  overflow: hidden;
  isolation: isolate;
  color: var(--c1);
  background: transparent;
  box-shadow: inset 0 0 0 2px var(--c1);
  transition: color calc(0.45s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-fill::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: var(--c1);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform calc(0.45s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-fill:hover {
  color: #fff;
}

.uv-fill:hover::before {
  transform: scaleX(1);
}
```

### React

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

const css = `
.uv-fill {
  font-family: -apple-system,BlinkMacSystemFont,"SF Pro Text","Inter",system-ui,sans-serif;
  font-size: var(--s);
  font-weight: 600;
  line-height: 1;
  padding: 1em 2em;
  border: 0;
  border-radius: 999px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  position: relative;
  overflow: hidden;
  isolation: isolate;
  color: var(--c1);
  background: transparent;
  box-shadow: inset 0 0 0 2px var(--c1);
  transition: color calc(0.45s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-fill::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: var(--c1);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform calc(0.45s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-fill:hover {
  color: #fff;
}

.uv-fill:hover::before {
  transform: scaleX(1);
}
`;

export default function BtnFill() {
  return (
    <>
      <style>{css}</style>
      <div
        style={{
          "--c1": "#0071e3",
          "--c2": "#8ec5ff",
          "--s": "16px",
          "--k": "1",
          "--fg": "#1d1d1f",
          "--bg": "#f5f5f7",
        } as CSSProperties}
      >
        <button className="uv-fill">Subscribe</button>
      </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 “Outline fill button” block (Buttons) from AIMRAN Library to my project.

## What it is
An outlined button that fills with color from left to right when the cursor moves over it.

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

## 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-fill {
  font-family: -apple-system,BlinkMacSystemFont,"SF Pro Text","Inter",system-ui,sans-serif;
  font-size: var(--s);
  font-weight: 600;
  line-height: 1;
  padding: 1em 2em;
  border: 0;
  border-radius: 999px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  position: relative;
  overflow: hidden;
  isolation: isolate;
  color: var(--c1);
  background: transparent;
  box-shadow: inset 0 0 0 2px var(--c1);
  transition: color calc(0.45s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-fill::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: var(--c1);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform calc(0.45s / var(--k)) cubic-bezier(.25,.1,.25,1);
}

.uv-fill:hover {
  color: #fff;
}

.uv-fill:hover::before {
  transform: scaleX(1);
}
`;

export default function BtnFill() {
  return (
    <>
      <style>{css}</style>
      <div
        style={{
          "--c1": "#0071e3",
          "--c2": "#8ec5ff",
          "--s": "16px",
          "--k": "1",
          "--fg": "#1d1d1f",
          "--bg": "#f5f5f7",
        } as CSSProperties}
      >
        <button className="uv-fill">Subscribe</button>
      </div>
    </>
  );
}
```

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