svelte-preprocess VS PostCSS

You can learn more about the official svelte-preprocess and other available config here

svelte-preprocess is responsible for processing things like TypeScript and SCSS. The svelte compiler itself is only responsible for turning the svelte file into JavaScript.

svelte-preprocess should handle scss out-of-the-box, and it’s included in SvelteKit by default if you created your project with create-svelte

// svelte.config.js import sveltePreprocess from 'svelte-preprocess' export default { // Consult https://github.com/sveltejs/svelte-preprocess // for more information about preprocessors // **here -> postcss: true** preprocess: sveltePreprocess({ postcss: true, }) }

/** @type {import('@sveltejs/kit').Config} */ const config = { // Consult https://github.com/sveltejs/svelte-preprocess // for more information about preprocessors preprocess: preprocess({ typescript: true, postcss: true, scss: { prependData: @import 'src/styles/helpers/functions.scss'; } }), kit: { paths: { assets: '', base: dev ? '' : '/route/in/website' }, trailingSlash: 'always', adapter: adapter({ pages: 'build', assets: 'build', fallback: 'index.html' }), files: { hooks: 'src/hooks', }, prerender: { default: true, }, } };

Continue to use tags

In svelte.config.js ... (import aliases can be whatever you want)

1. import svelte_preprocess from 'svelte-preprocess'
2. import autoprefixer from 'autoprefixer'
3. pass the Svelte preprocessor to Kit's preprocess config option and pass the postcss plugin to that Svelte preprocessor:

svelte.config.js

import svelte_proprocess from 'svelte-process'
import autoprefixer from 'autoprefixer'

const config = {
    // Consult https://github.com/sveltejs/svelte-preprocess for more info
    preprocess: [
        svelte_preprocess({
            postcss: {
                plugins: [autoprefixer()]
            }
        })
    ]
}

import adapter from '@sveltejs/adapter-auto'; import preprocess from 'svelte-preprocess'; import { mdsvex } from 'mdsvex'; import remarkMath from 'remark-math'; import rehypeKatex from 'rehype-katex-svelte'; /** @type {import('@sveltejs/kit').Config} */ const config = { extensions: ['.svelte', '.svx', '.md'], // Consult https://github.com/sveltejs/svelte-preprocess // for more information about preprocessors preprocess: [ preprocess(), mdsvex({ extensions: ['.svx', '.md'], smartypants: true, layout: { project: "./src/routes/projects/layout.svelte", post: "./src/routes/blog/layout.svelte", }, remarkPlugins: [remarkMath], rehypePlugins: [rehypeKatex], }), ], kit: { adapter: adapter({ edge: false, external: [], split: false }) } }; export default config;

Have you tried https://github.com/sveltejs/svelte-preprocess

// We have changed the adapter line to use adapter-node@next import adapter from '@sveltejs/adapter-node@next'; import preprocess from 'svelte-preprocess'; /** @type {import('@sveltejs/kit').Config} */ const config = { // Consult https://github.com/sveltejs/svelte-preprocess // for more information about preprocessors preprocess: preprocess(), kit: { // We have changed this to point to a build directory adapter: adapter({ out: 'build' }) } }; export default config;

the plugins in the official PostCSS website were old like IE6 or the marquee tag, and

Hello internet. I just published a new blog post on how to implement dark mode with SvelteKit, optionally with PostCSS and TailwindCSS:

There are many frontend tools available for this purpose. For example, PostCSS is a popular CSS processor that can combine and minimize your code. With the right plugin, it can even fix your code for compatibility issues, making sure your CSS styles work for all browsers.

I use PostCSS to extend CSS’s features and to add a few things that make writing styles a little more convenient, but it could easily be swapped for another preprocessor like Sass or vanilla CSS. It’s up to you. You can view my PostCSS config here.

Code transpilation isn't specific to JavaScript, You can also add a level of transformation to your CSS source using tools like post-css. Most languages with a fairly mature ecosystem will probably have some tools to help with code transformation.

In large projects, it is still a good idea to use PostCSS, which will translate new CSS features to something that browsers understand today.

LiveCodes provides many of the commonly used developer tools. These include Monaco editor (that powers VS Code), Prettier, Emmet, Vim/Emacs modes, Babel, TypeScript, SCSS, Less, PostCSS, Jest and Testing Library, among others. All these tools run seamlessly in the browser without any installations or configurations. It feels like a very light-weight version of your own local development environment including the keyboard shortcuts, IntelliSense and code navigation features.

Usually, one of the first things I do on creating a new web app is to throw a UI library in to help style components. There are several UI libraries that can be used by Svelte, but in this case I went with daisyUI because it's a fairly popular UI library which includes tailwind. To install daisyUI, you first need to install tailwind. There's a few different ways to do this (such as this guide), but the easiest way I've found is the following command, which also adds PostCSS and AutoPrefixer:

Vanilla CSS has taken a similar path with ambitious working drafts, better browser support, and PostCSS to fill the gap for user agents lagging behind. So why is Sass/SCSS still so popular? Maybe we go so used to it that we might have forgotten what problems it was meant to solve in the first place.