# inset-block-start

> Applies `inset-block-start` — the leading block edge, the top edge in a horizontal writing mode.

```ts
import { insBs } from "@sdxc/u/layout";
```

Applies `inset-block-start` — the leading block edge, the top edge in a
horizontal writing mode.

## Quick reference

Every documented call, beside the CSS it emits.

| Call | CSS |
| --- | --- |
| `u.insBs(4)` | `css({ insetBlockStart: "calc(var(--ui-spacing, 0.25rem) * 4)" })` |

## Examples

### Basic example

Use `insBs(n)` to set the `inset-block-start` offset of a positioned element from the spacing scale, the top edge in horizontal text:

```tsx
<div mix={[...]}>
	<div mix={[relative(), is(48), bs(32), ...]}>
		<div mix={[absolute(), insBs(0), ...]}>insBs(0)</div>
	</div>
	<div mix={[relative(), is(48), bs(32), ...]}>
		<div mix={[absolute(), insBs(6), ...]}>insBs(6)</div>
	</div>
</div>
```

## Using a custom value

Every scale argument also takes a raw CSS value, which passes through untouched.

```ts
u.insBs("2.75rem")
```

## Applying on a state

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

```ts
u.hover(u.insBs(4))
```

## Responsive design

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

```ts
u.at("md", u.insBs(4))
```

## Customizing your theme

### Customizing spacing

Every numeric step multiplies `--ui-spacing`, so redefining it rescales every spacing and sizing utility at once:

```css
:root {
	--ui-spacing: 0.25rem;
}
```

Every call that names the step now reads the new value:

```ts
insBs(4)
```

## Signature

```ts
u.insBs(value: SpacingValue)
```