Fix 3-button navigation

app/src/main/java/com/hippo/ehviewer/ui/EhActivity.kt

@@ -55,6 +55,7 @@ abstract class EhActivity : AppCompatActivity() {
         layoutInflater.factory2 = LayoutInflaterFactory(delegate).addOnViewCreatedListener(WindowInsetsHelper.LISTENER)
         super.onCreate(savedInstanceState)
         WindowCompat.getInsetsController(window, window.decorView).isAppearanceLightStatusBars = !isNightMode()
+        WindowCompat.getInsetsController(window, window.decorView).isAppearanceLightNavigationBars = !isNightMode()
         (application as EhApplication).registerActivity(this)
     }