Hi Cindy,
I understand the issue, but it is not possible for a form element to be embedded in another form element (HTML specification rule), that is why I am referring to a possible CSS issue.
From the looks of it, there is probably only a higher specificity CSS rule adding a top box-shadow/border to the input field. (it’s basically applying on the input field of the replaced element, causing the visual problem). The outside of the box looks okay, but the input field looks like to have the override styles from the theme. If I can see it, then I can probably suggest a small custom CSS snippet, that will remove that border 🙂
Let me know!