Wire guest branding theme

resources/js/guest/pages/__tests__/UploadPageImmersive.test.tsx

@@ -1,6 +1,6 @@
 import React from 'react';
 import { describe, expect, it, vi } from 'vitest';
-import { render, waitFor } from '@testing-library/react';
+import { render, screen, waitFor } from '@testing-library/react';
 import UploadPage from '../UploadPage';
 
 vi.mock('react-router-dom', () => ({
@@ -73,4 +73,15 @@ describe('UploadPage immersive mode', () => {
       expect(document.body.classList.contains('guest-immersive')).toBe(true);
     });
   });
+
+  it('centers the capture button within the countdown ring', () => {
+    render(<UploadPage />);
+
+    const captureButton = screen.getByRole('button', { name: 'upload.buttons.startCamera' });
+    const wrapper = captureButton.parentElement;
+
+    expect(wrapper).not.toBeNull();
+    expect(wrapper?.className).toContain('items-center');
+    expect(wrapper?.className).toContain('justify-center');
+  });
 });