Fix single css build issue

Author: owjs3901

apps/landing/next.config.ts

@@ -1,6 +1,11 @@
+import { dirname, join } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
 import { DevupUI } from '@devup-ui/next-plugin'
 import createMDX from '@next/mdx'
 
+const appRoot = dirname(fileURLToPath(import.meta.url))
+
 const withMDX = createMDX({
   extension: /\.mdx?$/,
 })
@@ -13,6 +18,8 @@ export default withMDX(
       reactCompiler: true,
     },
     {
+      devupFile: join(appRoot, 'devup.json'),
+      distDir: join(appRoot, 'df'),
       singleCss: process.env.DEVUP_SINGLE_CSS === '1',
     },
   ),