rollup-plugin-lit-css

Rollup plugin to import css files as JavaScript tagged-template literal objects.

The "Lit" stands for "Literal"

You can use it to import CSS for various libraries like lit-element, @microsoft/fast-element, or others.

Do I Need This?

No. This is an optional package who's sole purpose is to make it easier to write CSS-in-CSS while working on lit-element projects. You can just as easily write your CSS in some 'styles.css.js' modules a la:

import { css } from 'lit-element';
export default css`:host { display: block; }`;

And this may actually be preferred.

Hopefully this package will become quickly obsolete when the CSS Modules Proposal (or something like it) is accepted and implemented.

In the mean time, enjoy importing your CSS into your component files.

Options

Name	Accepts	Default
include	Array of glob of files to include.	['**/*.css']
exclude	Array of glob of files to exclude.	undefined
uglify	Boolean or Object of uglifycss options.	false
specifier	Package to import css from	lit
tag	Name of the template-tag function	css

Usage

import config from './rollup.config.rest.js'
import litcss from 'rollup-plugin-lit-css';

export default {
  ...config,
  plugins: [
    litcss({ include, exclude, uglify })
  ]
}

Then import your CSS:

:host {
  display: block;
}

h1 {
  color: hotpink;
}

import { LitElement, customElement, html } from 'lit-element';

import style from './css-in-css.css';

@customElement('css-in-css')
class CSSInCSS extends LitElement {
  static get styles() {
    return [style];
  }

  render() {
    return html`<h1>It's Lit!</h1>`;
  }
}

Usage with FAST

plugins: [
  litcss({ specifier: '@microsoft/fast-element' })
]

import { FASTElement, customElement, html } from '@microsoft/fast-element';

import styles from './css-in-css.css';

const template = html<CSSinCSS>`<h1>It's Lit!</h1>`;

@customElement({ name: 'css-in-css', template, styles })
class CSSinCSS extends FASTElement {}

Looking for webpack? lit-css-loader Looking for esbuild? esbuild-plugin-lit-css

Upgrade from version 2.x

Starting with version 3.x, the default import used when transforming the CSS files is lit (see specifier option above) which is LitElement 3.x. If you need this package to work with LitElement 2.x, you have to set the specifier to lit-element like so:

import config from './rollup.config.rest.js'
import litcss from 'rollup-plugin-lit-css';

export default {
  ...config,
  plugins: [
    litcss({ specifier: 'lit-element' })
  ]
}