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Previous Article: 📝Integrating Tailwindcss With Eleventy

In my previous post I wrote about using a nunjucks filter for integrating postcss (& tailwindcss) to eleventy.

I have been playing around with eleventy transforms for html minification so thought why not use a transform to run postcss instead of using a nunjucks filter.

Using a Transform #

Using a transform means we can inject content into html pages which means we can inject a style element inside of head for inline css.

I based this on the html minifier example in the 11ty docs.

// PostCSS transform
    async (contentInput, outputPath) => {
      let content = contentInput
      if (outputPath && outputPath.endsWith('.html')) {
        const cssInput = fs.readFileSync('src/_styles/_global.css', {
          encoding: 'utf-8',
        const minified = await postcss([
          .process(cssInput, { from: undefined })
          .then((r) => {
            return r.css
        content = content.replace(
      return content

The speed is similar to using the nunjucks filter.

[11ty] Benchmark    896ms  33%    25× (Configuration) "postcss-trans" Transform
[11ty] Copied 11 files / Wrote 25 files in 2.39 seconds (95.6ms each, v2.0.1)
[11ty] Benchmark    977ms  34%    23× (Configuration) "postcss" Nunjucks Async Filter
[11ty] Copied 11 files / Wrote 26 files in 2.61 seconds (100.4ms each, v2.0.1)

This could be useful for people not using nunjucks.

Source Code #

The source for my 11ty blog is available on github.