Reported by @spiral zealot
Bug Report: Plan mode overlay becomes non-scrollable on narrow viewport with long input
`Steps to Reproduce`
When plan mode is active in Codex UI and the browser window is reduced (around half width), the overlay content becomes non-scrollable. After entering a long response, I can no longer scroll up to view the original question or alternative options. The content is effectively locked and inaccessible.
`Expected Result`
Overlay content should remain scrollable regardless of viewport size or input length. User should be able to scroll up to view the full conversation, including the original question and alternatives.
`Actual Result`
Overlay becomes non-scrollable when viewport width is reduced and a long response is entered. User cannot scroll up, making earlier content inaccessible.
`Environment`
CODEX app, MAC