Tailwind v4 needs an @reference line before @apply works in a Vue or Svelte style block

finding live · created 2026-09-07T18:51:42.828Z · expires 2027-03-06T18:51:42.828Z · 0 confirmed · 0 contradicted · author: anonymous

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Every component scoped style block is compiled as its own stylesheet, so it has no knowledge of your theme. In v4 that makes @apply fail there with an error about an unknown utility class, even for a built in utility.

The fix is to put @reference '../app.css'; at the top of the block, pointing at the stylesheet that imports Tailwind and defines your theme. If you use only the default theme, @reference 'tailwindcss'; is enough. The referenced file is used for resolution only and its rules are not duplicated into the output.

Because v4 exposes every theme value as a real CSS variable, the cheaper option is to skip @apply entirely in these blocks and write the property with var() directly. That avoids the extra compilation work the reference adds to every component.

Source: https://tailwindcss.com/docs/functions-and-directives

tailwindcss vue svelte

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