diff --git a/pkgs/webview-ui/app/eslint.config.mjs b/pkgs/webview-ui/app/eslint.config.mjs
index df02ea988..858cc8fec 100644
--- a/pkgs/webview-ui/app/eslint.config.mjs
+++ b/pkgs/webview-ui/app/eslint.config.mjs
@@ -18,7 +18,7 @@ export default tseslint.config(
         },
       ],
       "tailwindcss/no-custom-classname": [
-        "warn",
+        "error",
         {
           callees: ["cx"],
           whitelist: ["material-icons"],