Using the :global(...) CSS selector causes an error when using Sass's indented syntax.

[elliotwaite]

Trying to use the css global selector (:global(...)) causes a syntax error when trying to use Sass's indented syntax.

Here is the code to reproduce the issue (adapted from the sveltejs/template).

App.svelte:

<style type="text/sass">
:global(h1)
  color: purple
</style>

<h1>Hello world!</h1>

Then this was added to rollup.config.js:

import { sass } from 'svelte-preprocess-sass';
...
svelte({
  ...
  preprocess: {
    style: sass({indentedSyntax: true}),
  },
  ...

The full rollup.config.js:

import svelte from 'rollup-plugin-svelte';
import resolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import livereload from 'rollup-plugin-livereload';
import { terser } from 'rollup-plugin-terser';
import { sass } from 'svelte-preprocess-sass';

const production = !process.env.ROLLUP_WATCH;

export default {
  input: 'src/main.js',
  output: {
    sourcemap: true,
    format: 'iife',
    name: 'app',
    file: 'public/bundle.js'
  },
  plugins: [
    svelte({
      // enable run-time checks when not in production
      dev: !production,
      preprocess: {
        style: sass({indentedSyntax: true}),
      },
      // we'll extract any component CSS out into
      // a separate file — better for performance
      css: css => {
        css.write('public/bundle.css');
      }
    }),

    // If you have external dependencies installed from
    // npm, you'll most likely need these plugins. In
    // some cases you'll need additional configuration —
    // consult the documentation for details:
    // https://github.com/rollup/rollup-plugin-commonjs
    resolve(),
    commonjs(),

    // Watch the `public` directory and refresh the
    // browser on changes when not in production
    !production && livereload('public'),

    // If we're building for production (npm run build
    // instead of npm run dev), minify
    production && terser()
  ],
  watch: {
    clearScreen: false
  }
};

Error message:

Error: Invalid CSS after "": expected 1 selector or at-rule, was "global(h1): {"

Any suggestions for how to fix this issue?

[Conduitry]

This doesn't sound like an issue with Svelte. I skimmed the linked svelte-preprocess-sass issue, and it sounds like the syntax just isn't valid indented sass. What specifically are you suggesting should happen?

[elliotwaite]

Ah, you're right. Just found a solution that makes it valid sass syntax! Adding a backslash escape character \:global(...) makes it work.

<style type="text/sass">
\:global(h1)
  color: purple
</style>

Thanks for taking the time to look into this.