<item name="android:windowTranslucentNavigation">true</item>
<item name="android:windowTranslucentStatus">true</item>

Window window = getWindow();
    window.setNavigationBarColor(0x66000000); // (или <item name="android:navigationBarColor">@color/black_40</item>)
    window.setStatusBarColor(0x66000000); // (или <item name="android:statusBarColor">@color/black_40</item>)
    window
        .getDecorView()
        .setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION);