[dev-overlay] fix: overlay is located relatively low when long content (#76113)
### Why?
The overlay seemed too low when the content was long since it had both
`padding` and `top` values. Adjust to have only the `top` and preserve
the `padding` value.
### Before
https://github.com/user-attachments/assets/e2172a7b-1275-4647-88e2-7b91fc4c8d98
### After
https://github.com/user-attachments/assets/182cfa7b-d532-4bb7-aa0c-69911720b370
Closes NDX-845