QAlaunch

v0 preview doesn't match the deployed site: how to fix it

When a v0 preview looks right but the deployed Vercel site is unstyled or laid out differently, the project usually has two globals.css files and app/layout.tsx imports the wrong one, or two PostCSS/Tailwind config files are fighting each other. The v0 preview and the Vercel build do not resolve files in exactly the same way, so a conflict that is invisible in one shows up in the other. Keep one stylesheet and one config of each kind, then redeploy without the build cache.

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What you'll see

In the v0 chat the page looks finished. On the vercel.app address or your own domain the same page shows plain serif text, buttons with no colour, cards stacked in a single column, or spacing that is completely off. Sometimes only one colour or one component is different, which makes it look like a design bug rather than a build problem.

Why it happens

1. Two globals.css files, and the layout imports the wrong one

v0 sometimes creates app/globals.css and styles/globals.css in the same project. The preview may pick up the one with your Tailwind layers while the production build follows the import in app/layout.tsx to the other, nearly empty file. This is the one cause Vercel staff confirmed in their own investigation thread.

2. Duplicate PostCSS or Tailwind config files

A project that has both postcss.config.js and postcss.config.mjs, or an old tailwind.config.ts next to a Tailwind v4 setup that expects configuration inside the CSS file, can build with the wrong one. The result is a stylesheet that compiles but is missing most of its utility classes.

3. A stale build cache on Vercel

Vercel reuses build output between deployments to save time. In a few community reports a config change did not take effect until the project was rebuilt from scratch, so the old, broken CSS kept being served.

4. Something on the live page blocks the stylesheet

If the CSS file itself returns a 404, or a script error stops client-side components from mounting, the page looks broken even though the code is fine. This is why Vercel staff ask for the browser console and network tab first.

How to fix it

  1. Open the deployed page, press F12, and look at the Network tab filtered to CSS. Note whether the stylesheet under /_next/static/css/ loads with status 200 and how large it is. A tiny file points to the wrong globals.css; a 404 points to a build or path problem.
  2. In v0, open the code view and search the file tree for globals.css. If there are two, decide which one holds your @tailwind or @import "tailwindcss" lines and theme variables, and delete the other.
  3. Open app/layout.tsx and check the stylesheet import at the top. It must point at the file you kept, for example ./globals.css when it sits in app/, or ../styles/globals.css when it sits in styles/.
  4. Look in the project root for more than one postcss.config or tailwind.config file. Keep the one that matches the Tailwind version in package.json and remove the rest.
  5. Push the change, then in the Vercel dashboard open Deployments, choose the latest deployment, click Redeploy and untick Use existing Build Cache so the CSS is rebuilt from nothing.
  6. If the page still differs, duplicate the v0 project and deploy the copy. A clean copy that looks right means the original deployment pipeline was holding on to something old.

Prompt to paste into v0

The deployed site's styling differs from the v0 preview. Find every globals.css, postcss.config and tailwind.config file in the project. Keep a single correct one of each for the Tailwind version in package.json, make sure app/layout.tsx imports the globals.css you kept, delete the duplicates, and list exactly which files you removed or changed.

How to check it's fixed

  • Open the production URL in a private window at desktop width and at phone width and compare it with the v0 preview side by side.
  • In DevTools Network, confirm every CSS request returns 200 and the main stylesheet is a reasonable size, not a few hundred bytes.
  • Reload with the Console open and confirm no red errors appear before the page finishes rendering.

What a QAlaunch scan shows for this

  • Desktop and 390px phone screenshots of the live page, so an unstyled or collapsed layout is visible next to what you expected.
  • Failed network requests for stylesheets or scripts, with the URL and status code.
  • JavaScript console errors that stop components from rendering.
  • Horizontal overflow at phone width when missing utility classes leave elements at their full desktop size.

See exactly what a full report contains in the sample report.

Frequently asked questions

Why does it look right in v0 but not on Vercel?

The v0 preview is a fast development render, while Vercel runs a full production build. Duplicate files, import paths and cached config are resolved differently between the two, so the same code can produce different CSS.

Will asking v0 to fix the styling help?

Only if you tell it what is wrong. Asking it to restyle the page often adds more CSS on top of the conflict. Point it at the duplicate files instead, using the prompt on this page.

Do I lose anything by redeploying without the build cache?

No. The build just takes longer because dependencies and assets are processed again. Your code, domains and environment variables stay the same.

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Related fixes

More for v0: all v0 fixes · v0 testing

Written by Waqas Ahmad, QA engineer with 10 years of professional testing experience. Last checked October 26, 2026.

Sources: Vercel Community: v0 preview does not match Vercel deployment · Vercel Community: deployed layout crashed, fine in v0 preview · Vercel Community: deploy is different from v0 preview