add theme provider

src/renderer/index.tsx

@@ -1,9 +1,18 @@
 import { createRoot } from 'react-dom/client';
 import App from './App';
 
+import { ThemeProvider, CssBaseline } from '@mui/material';
+import { defaultTheme } from '../theme/themes'; // <-- поправь путь, если themes.ts лежит в другом месте
+
 const container = document.getElementById('root') as HTMLElement;
 const root = createRoot(container);
-root.render(<App />);
+
+root.render(
+  <ThemeProvider theme={defaultTheme}>
+    <CssBaseline />
+    <App />
+  </ThemeProvider>,
+);
 
 // calling IPC exposed from preload script
 window.electron?.ipcRenderer.once('ipc-example', (arg) => {