Add Close Sidebar Functionality for Better Mobile Experience

[devleejb]

What would you like to be added:
Currently, there is no functionality to close the sidebar located on the left side of the screen.
This lack of feature becomes particularly inconvenient in mobile environments.
Therefore, it is requested to add a close sidebar functionality to improve the user experience, especially on mobile devices.

Why is this needed:
To address the inconvenience and provide better usability for users accessing �CodePair on mobile devices.

Additional Information: