diff --git a/src/App.jsx b/src/App.jsx
index 26c5c85..87f4a58 100644
--- a/src/App.jsx
+++ b/src/App.jsx
@@ -1,15 +1,17 @@
 import { useState, useEffect } from 'react'
 import { generateToken, loadState, saveState } from './api.js'
 import { createState } from './gameState.js'
-import Game from './Game.jsx'
+import Ledger from './screens/Ledger.jsx'
 import './App.css'
 
 const TOKEN_KEY = 'otivm_token'
+const SCREENS = ['ledger', 'map']
 
 export default function App() {
   const [state, setState] = useState(null)
   const [token, setToken] = useState(null)
   const [loading, setLoading] = useState(true)
+  const [screen, setScreen] = useState('ledger')
 
   useEffect(() => {
     async function bootstrap() {
@@ -45,5 +47,35 @@ export default function App() {
     )
   }
 
-  return <Game state={state} onStateChange={onStateChange} />
+  return (
+    <div>
+      <nav className="main-nav">
+        <span className="nav-title">OTIVM</span>
+        <div className="nav-links">
+          <button
+            className={`nav-btn${screen === 'ledger' ? ' active' : ''}`}
+            onClick={() => setScreen('ledger')}
+          >
+            Ledger
+          </button>
+          <button
+            className={`nav-btn${screen === 'map' ? ' active' : ''}`}
+            onClick={() => setScreen('map')}
+          >
+            Map
+          </button>
+        </div>
+      </nav>
+      <div className="screen-wrap">
+        <div style={{ display: screen === 'ledger' ? 'block' : 'none' }}>
+          <Ledger state={state} onStateChange={onStateChange} />
+        </div>
+        <div style={{ display: screen === 'map' ? 'block' : 'none' }}>
+          <div className="placeholder">
+            <p>Map — coming in OTIVM-II</p>
+          </div>
+        </div>
+      </div>
+    </div>
+  )
 }
diff --git a/src/Game.jsx b/src/screens/Ledger.jsx
similarity index 100%
rename from src/Game.jsx
rename to src/screens/Ledger.jsx