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https://github.com/pierreburel/sass-em

Sass function and mixin to convert px in em.
https://github.com/pierreburel/sass-em

css em sass scss

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Sass function and mixin to convert px in em.

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# sass-em [![Node.js CI](https://github.com/pierreburel/sass-em/actions/workflows/node.js.yml/badge.svg)](https://github.com/pierreburel/sass-em/actions/workflows/node.js.yml)

Sass function and mixin to convert px in em.

## Breaking changes

- **3.0**: changed default function name when imported globally (`@use "rem" as *;` or `@import "sass-rem";`) to `em-convert` to match [sass-rem](https://github.com/pierreburel/sass-rem), as [CSS now use `rem()` for calculating the remainder](https://developer.mozilla.org/en-US/docs/Web/CSS/rem). It shouldn't change anything if you used Sass Modules introduced in 2.0 (`em.convert`).

- **2.0**: now using [Sass Modules](https://sass-lang.com/blog/the-module-system-is-launched), using `@use` and `em` is renamed to `em.convert`. You could still use `@import` with no changes (see usage below), but **if you need LibSass/node-sass and Ruby Sass support (both deprecated), you should stay on 1.0** (which works fine) or use the [PostCSS](https://github.com/pierreburel/postcss-em) version.

---

## Installation

Install with [Yarn](https://yarnpkg.com/) or [npm](https://www.npmjs.com/):

* `yarn add sass-em`
* `npm install sass-em`

---

## Usage

The `em.convert` function takes at least 2 parameters: the value(s) (px, mixed) and the context (px).
There can be multiple values (eg. multiple box shadow), but **the last parameter must be the context**.

The `em.convert` mixin takes only 2 parameters: the properties (map of `property: value`) and the context (px). It can be used to convert the values of multiple properties with the same context.

Import in your project depending of your setup:

```scss
@use "em";
// or @use "~sass-em" as em;
// or @use "../node_modules/sass-em" as em;

$base-font-size: 16px;
$h1-font-size: 24px;

.demo {
font-size: em.convert($h1-font-size, $base-font-size); // Simple
border-bottom: em.convert(1px solid black, $h1-font-size); // Shorthand
box-shadow: em.convert(0 0 2px #ccc, inset 0 0 5px #eee, $h1-font-size); // Multiple values
// Multiple properties
@include em.convert((
margin: 20px 5%,
padding: 10px
), $h1-font-size);
}
```

Will output :

```css
.demo {
font-size: 1.5em;
border-bottom: 0.0416666667em solid black;
box-shadow: 0 0 0.0833333333em #ccc, inset 0 0 0.2083333333em #eee;
margin: 0.8333333333em 5%;
padding: 0.4166666667em;
}
```

## Namespace

You can change the namespace when importing and use `em` function and mixin instead of `convert`:

```scss
@use "em" as to; // Because why not?

.demo {
font-size: to.em(24px, 16px);
}
```

Or you can even load the library globally (but beware of conflicts, avoided by the idea of modules):

```scss
@use "em" as *;

.demo {
font-size: em-convert(24px, 16px);
}
```

---

## Legacy import

If you don't want to use Sass Modules, you can still use `@import` with `em-convert` function and mixin:

```scss
@import "sass-em";

.demo {
font-size: em-convert(24px);
}
```

---

## See also

- PostCSS version: https://github.com/pierreburel/postcss-em
- `sass-rem`: https://github.com/pierreburel/sass-rem