new navigation sidebar is effectively modal, keyboard-hostile, and hides the documentation from view

The not-yet-released python 3.10 and 3.11 docs theme introduces navigation sidebar behavior that is several steps backwards in usability. From what I can tell, it exhibits all these problems:

• When open, it covers up the documentation instead of letting the text reflow, making it impossible to follow my usual workflow of quickly jumping from one section to the next while reading the bits I need. The experience is like trying to navigate around modal dialog boxes in a 1990s Windows application.
• It is now inaccessible on systems without a mouse.
• Even on computers that have a mouse, viewing it is now a hassle. One must locate the mysterious hamburger button, move a hand to the mouse, aim it at the button, and click it, before the menu will appear at all. Only then can one go about looking for a needed navigation link. That's a lot of extra steps compared to simply having the links always available at the top, bottom, or side of the page.
• Scrolling through the navigation links no longer works without a mouse. Page Up/Down, arrow keys, and space bar all fail to scroll the content being read. Only mouse navigation seems to be supported.

This new design seems to have been implemented hastily, without consideration for users outside a very narrow range of workflows and devices. Please revert it, at least until something more sensible can be developed.

The issue identifies the new navigation sidebar in the Python 3.10 and 3.11 documentation theme; start by locating that sidebar's implementation and reproducing its mouse and keyboard behavior. Done should mean the documentation remains usable while navigating, the sidebar does not obscure the text, and keyboard users can access and scroll the navigation.