CSS is not included for some Tailwind classes in Pug template (in Vue)

[davidrunger]

What version of Tailwind CSS are you using?

v4.0.14 (the latest released version, at the time of writing)

What build tool (or framework if it abstracts the build tool) are you using?

Vite 6.2.2, Vue 3.5.13, Pug 3.0.3 (the latest released version of each, at the time of writing)

What version of Node.js are you using?

v22.14.0 (the latest LTS release, at the time of writing)

What browser are you using?

Firefox (though I don't think it's relevant)

What operating system are you using?

Linux (Debian / MX Linux) (though I don't think it's relevant)

Reproduction URL

I cannot provide a Tailwind Play URL, because I think that this bug occurs only in Pug templates, whereas Tailwind Play only supports plain HTML.

But here's a public GitHub repo with a minimal reproduction: https://github.com/davidrunger/tailwind-pug-bug-demo

And here's that GitHub repo imported into CodeSandbox: https://codesandbox.io/p/github/davidrunger/tailwind-pug-bug-demo/main?file=%2Fsrc%2FApp.vue

Describe your issue

CSS styles are sometimes not included for some Tailwind classes in Pug templates in my Vue project.

In the reproduction linked above, there is this Vue component:

<template lang="pug">
.bg-neutral-900.text-red-500 This is a test.
</template>

When viewed in the browser, only the text-red-500 class has any visible effect (making the text red). The bg-neutral-900 class does not have any effect (when served either via the Vite hot-reloading dev server or when compiled and viewed via the Vite static production preview server).

Live dev server:

Compiled production server:

I expect that the bg-neutral-900 class in the Pug Vue template would cause Tailwind to include CSS that gives that text a dark background, which is what happens if we go back to tailwindcss and @tailwindcss/vite at v4.0.9 :

Live dev server:

Compiled production server:

Thank you for Tailwind and for taking a look at this bug!

Edit: The bug also occurs when using the Tailwind PostCSS plugin, rather than the Tailwind Vite plugin (when using Tailwind v4.0.14, and not when using Tailwind v4.0.9). I pushed a branch use-tailwind-postcss-plugin to the minimal bug reproduction repo that demonstrates this.

[RobinMalfait]

Hey!

This has been fixed by #17252 and will be available in the next release.

[davidrunger]

Wow, thank you for the incredibly quick fix, @RobinMalfait ! 🙇‍♂️ 🙌