[Bug]: Floating open/close assistant tab for wider displays

[stephprince]

What happened?

See comment in #2140 (comment).

Steps to Reproduce

Use the dev build of the documentation on a larger display: https://pynwb.readthedocs.io/en/dev/

Operating System

macOS

Python Executable

Conda

Python Version

3.9

Package Versions

No response

Code of Conduct

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