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How to install TailwindCSS on Angular 19 that uses SCSS?

I have an Angular 19 app which uses SCSS and I have TailwindCSS 3.4.17 setup and it works.

Now I wanna upgrade to TailwindCSS v4. I follow the official instructions to install it on Angular from here and I get errors.

[WARNING] Deprecation [plugin angular-sass]

src/styles/_tailwind.scss:1:8:
  1 │ @import "tailwindcss";
    ╵         ^

So I do @use "tailwindcss"; and that's gone. But I also get:

X [ERROR] Cannot apply unknown utility class: bg-gray-100 [plugin angular-sass]

node_modules/tailwindcss/dist/lib.js:17:296:
  17 │ ...r,{onInvalidCandidate:x=>{throw new Error(`Cannot apply

unknown... ╵

So I removed all the @apply in my scss files.

The error was gone but the tailwind.config.js was not used. Turns out the docs says:

JavaScript config files are still supported for backward compatibility, but they are no longer detected automatically in v4.

If you still need to use a JavaScript config file, you can load it explicitly using the @config directive:

CSS @config "../../tailwind.config.js";

So I added the @config file to _tailwindcss.scss which is included in my styles.scss file. I got errors again:

The plugin "angular-sass" was triggered by this import

angular:styles/global:styles:2:8:
  2 │ @import 'src/styles.scss';

So my question is basically this:

  • What is going on with TailwindCSS team?
  • Why they don't support SCSS?
Solution

  • Note: Although I wanted to mark it as a duplicate of a similar answer, the question is entirely different-only the conclusion is similar. Therefore, I'll leave the relevant parts of the documentation here. The key point is that starting from TailwindCSS v4, no preprocessor is needed anymore.

    Deprecated: preprocessors support

    Sass, Less, and Stylus

    Tailwind CSS v4.0 is a full-featured CSS build tool designed for a specific workflow, and is not designed to be used with CSS preprocessors like Sass, Less, or Stylus.

    Think of Tailwind CSS itself as your preprocessor — you shouldn't use Tailwind with Sass for the same reason you wouldn't use Sass with Stylus.

    Since Tailwind is designed for modern browsers, you actually don't need a preprocessor for things like nesting or variables, and Tailwind itself will do things like bundle your imports and add vendor prefixes.

    Sorry for the inconvenience here, however right now we don't support migrating .scss or .less files. Doing so would require us to be able to understand the scss/sass and less syntax to make changes. But even if we do that, Tailwind CSS v4 isn't really compatible with these files anyway.

    I would recommend to see if you can rename the file(s) to .css and try again. You might notice that sometimes people use scss for features such as nested css, which should just work already in Tailwind CSS v4 (and modern browsers). So there is a good chance that you might not need .scss files at all.

    Again, sorry about the inconvenience here, but if you can migrate to normal .css files, then upgrading using the upgrade tool should just work.

    Simply put, TailwindCSS v4 removes the need for Sass and other preprocessors. The TailwindCSS v4 ecosystem can independently provide the functionality that these preprocessors offered.