Bug - Date picker - "calendar" element needs border, mark for removal

<img width="259" height="144" alt="Image" src="https://github.com/user-attachments/assets/e9f00777-408b-4fb7-ada4-816fcac46efe" />

Just needs a border for now. That element isn't in use with react, so I'm guessing it's a straggler from before we used menu/popover and popper and we never removed it. If that looks to be the case, leave a TODO comment to remove it in a breaking change.