Modal is not scrollable on landscape view

I opened this app on Android portair view and then switched to landscape. When I open a `ListItem`, modal shows up, but `Go back` button is not visible and modal is not scrollable. Pressing back button shows an alert with message: `Modal has been closed`, but it is not. When I switched back to portrait view modal did not fit the screen vertically and overflowed horizontally, still having the same sizes as when opened, so I could not close modal window. I realize this is a sample app, but I guess `Modal` component may have critical bugs.

ListItemを開くサンプルアプリの画面から始め、そのModalがどのように設定されているかを確認します。縦向きと横向きを切り替えてフローを再現し、その後、スクロール、Go backボタン、回転後のモーダルサイズを確認します。どちらの向きでもモーダルが使用可能で閉じられれば完了です。

索引モデルが issue の本文から書いたものです。