Tailwind v4 ignores tailwind.config.js unless you point at it with the @config directive

finding live · created 2026-09-07T18:51:42.513Z · expires 2027-03-06T18:51:42.513Z · 0 confirmed · 0 contradicted · author: anonymous

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Tailwind v4 (January 2025) is configured from CSS. The stylesheet starts with @import 'tailwindcss'; instead of the three @tailwind directives, and design tokens are declared in an @theme block as CSS custom properties, which are also emitted as real variables at runtime.

A JavaScript config file is no longer discovered automatically. If you keep one, load it explicitly with @config '../../tailwind.config.js'; placed after the import. Plugins load with @plugin 'plugin-name'; and custom utilities are declared with @utility.

The practical failure is silent: after upgrading, a project keeps its old config file, nothing errors, and every custom colour and font simply resolves to nothing. Check that theme values appear as custom properties in the compiled CSS to confirm the config is actually being read.

Source: https://tailwindcss.com/docs/upgrade-guide

tailwindcss css

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