# grayscale

> Applies a `filter: grayscale(...)`, desaturating toward grey; `1` (the default) is fully grey, dimming an inactive element while its layout holds.

```ts
import { grayscale } from "@sdxc/u/effects";
```

Applies a `filter: grayscale(...)`, desaturating toward grey; `1` (the
default) is fully grey, dimming an inactive element while its layout holds.
Purely visual, so pair it with a cue assistive technology can read.

## Quick reference

Every documented call, beside the CSS it emits.

| Call | CSS |
| --- | --- |
| `u.grayscale()` | `css({ "--ui-filter-grayscale": "1", filter: "... grayscale(var(--ui-filter-grayscale, 0)) ..." })` |

## Examples

### Basic example

Use `grayscale(n)` to desaturate an element toward grey, where `grayscale()` with no argument is fully grey:

```tsx
<div mix={[...]}>
	<div mix={[...]}>
		<img mix={[grayscale(0.25), ...]} src={...} alt="" />
		<span mix={[...]}>grayscale(0.25)</span>
	</div>
	<div mix={[...]}>
		<img mix={[grayscale(0.5), ...]} src={...} alt="" />
		<span mix={[...]}>grayscale(0.5)</span>
	</div>
	<div mix={[...]}>
		<img mix={[grayscale(), ...]} src={...} alt="" />
		<span mix={[...]}>grayscale()</span>
	</div>
</div>
```

### Restoring color on hover

Set `grayscale()` and override it with `hover(grayscale(0))` to bring color back when the element is hovered. Hover the photograph:

```tsx
<img
	mix={[
		grayscale(),
		hover(grayscale(0)),
		transition("filter", { duration: 300 }),
		...,
	]}
	src={...}
	alt=""
/>
```

## Applying on a state

Wrap the call in a state utility to scope it to one selector.

```ts
u.hover(u.grayscale())
```

## Responsive design

Wrap the call in a container query to scope it to one width.

```ts
u.at("md", u.grayscale())
```

## Signature

```ts
u.grayscale(value?: number | (string & {}))
```