How to setup Tailwind with PurgeCSS and PostCSS

How I set up my workflow to trim the Tailwind CSS using PurgeCSS and a simple PostCSS setup (no webpack involved)

I recently set out to move my blog CSS to Tailwind.

Tailwind is an interesting framework because instead of providing a set of widgets like Bootstrap or others, it provides utilities.

I find it resonates a lot with how I work with HTML.

I introduced how I use Tailwind with Vue in a previous post, but without a build tool in place already, it can be hard to get the correct setup right, and I decided to write this blog post even just for me to remember later on 🙃

In this post I explain how to use Tailwind with any kind of project.

Install Tailwind

First step is to install Tailwind, using npm or yarn:

npm init -y
npm install tailwindcss

Create the configuration file

Next, use this command to create a configuration file:

npx tailwind init

This will create a tailwind.config.js file in the root of your project, adding the basic Tailwind configuration.

Configure PostCSS

Now you need to tweak the PostCSS configuration to make sure Tailwind runs. Add:

module.exports = {
  plugins: [
    require('tailwindcss'),
    require('autoprefixer')
  ]
}

to your postcss.config.js. Create one if it does not exist.

I also added autoprefixer for convenience, you’ll likely need it. Install it with npm install autoprefixer.

Oh, also make sure you installed PostCSS (npm install -g postcss-cli)

Create the Tailwind CSS file

Now create a CSS file where you want, like in tailwind.css and add

@tailwind base;
@tailwind components;
@tailwind utilities;

Create the build command

Now open your package.json file, and add a scripts section if you don’t have it:

"scripts": {
  "build:css": "postcss src/tailwind.css -o static/dist/tailwind.css"
}

Build Tailwind

Now from the command line run npm run build:css will build the final CSS file.

The resulting file is in static/dist/tailwind.css (you can change the location in the above command).

Automatically regenerate the CSS upon file changes

Every time I change something in the theme HTML (stored in the layouts folder in my case), I want to regenerate the CSS, and trigger the purge and minification I set up.

How to do this?

Install the watch npm package:

npm install watch

and add the watch script to your package.json file. You already had build:css from before, we just add a script that watches the layouts folder and runs build:css upon every change:

"scripts": {
  "build:css": "postcss src/tailwind.css -o static/dist/tailwind.css",
  "watch": "watch 'npm run build:css' ./layouts"
}

Now run npm run watch and you should be good to go!

Trim the file size

If you check, the resulting file is huge. Even if you don’t use any Tailwind class in your HTML, all of the framework is included by default, because that’s the default configuration in the tailwind.js file.

They decided to include all, to avoid people missing things. It’s a design choice. We now need to remove stuff, and it turns out we can use purgecss to remove all the unused CSS classes.

I also want to remove all comments from the CSS and make it as small as possible. cssnano is what we’re looking for.

We can automate this stuff! First, install those utilities:

npm install cssnano
npm install @fullhuman/postcss-purgecss

Then we add this to our PostCSS configuration file postcss.config.js:

const purgecss = require('@fullhuman/postcss-purgecss')
const cssnano = require('cssnano')

module.exports = {
  plugins: [
    require('tailwindcss'),
    require('autoprefixer'),
    cssnano({
      preset: 'default'
    }),
    purgecss({
      content: ['./layouts/**/*.html', './src/**/*.vue', './src/**/*.jsx'],
      defaultExtractor: content => content.match(/[\w-/:]+(?<!:)/g) || []
    })
  ]
}

In development, avoid too much processing

Why? Every step you add slows down the feedback cycle while developing. I use this config to only add prefixes and removing comments in production:

postcss.config.js

const purgecss = require('@fullhuman/postcss-purgecss')
const cssnano = require('cssnano')

module.exports = {
  plugins: [
    require('tailwindcss'),
    process.env.NODE_ENV === 'production' ? require('autoprefixer') : null,
    process.env.NODE_ENV === 'production'
      ? cssnano({ preset: 'default' })
      : null,
    purgecss({
      content: ['./layouts/**/*.html', './src/**/*.vue', './src/**/*.jsx'],
      defaultExtractor: content => content.match(/[\w-/:]+(?<!:)/g) || []
    })
  ]
}