[🐛 BUG ] Search Modal is getting overlapped by Sticky Nav

### Hi team! 👋 David here

Found this error on the docs page 🐛

So usually when you click on the Search bar or use `Ctrl+K` or `Cmd+k` you'll see something like this ⬇️


But, when you scroll just a little bit down to read the documentation and do the same thing, the Sticky Nav which indicates the current docs section where you currently are overlaps the Search Modal like this


### Expected behavior
I would expect to see something similar as the first image like this


Reproduce the issue on the documentation page by scrolling, then opening Search with the search bar or Ctrl+K/Cmd+K. Inspect the Search Modal and Sticky Nav entry points and their layering; done means the modal fully covers the nav and remains usable after scrolling.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.