Fix Next.js Tailwind Build

After upgrading my project to Next.js 15 I noticed that all Tailwind classes vanish the moment I run a production build (`npm run build && next start`). In development everything renders perfectly, so the issue is strictly in the compiled output.

Here’s the current setup:
• Tailwind is already imported and referenced in next.config.js.
• A postcss.config.js file is present with the usual `tailwindcss` and `autoprefixer` plugins.

I need someone to trace why Tailwind isn’t being processed during the build step, adjust whichever configuration, plugin, or dependency is at fault, and deliver a clean solution that leaves me with a working production bundle.

Acceptance criteria
• `next build` completes without errors or warnings related to Tailwind.
• Starting the server with `next start` shows all styles exactly as in development mode.
• A concise explanation (read-me or comments) of the changes so I can reproduce the fix on other environments.