Mobile/compact menu does not behave like other ‘hamburger menus’

[ChrisXKeroack]

Describe the bug
Compact menu does not behave like a typical compact menu

To Reproduce
Steps to reproduce the behavior:

1. https://openfl.readthedocs.io/en/latest/index.html
2. Resize window to a narrow enough width to get the mobile/compact layout
3. Use keyboard, mouse and screenreader to interact with the 'hamburger menu' element

Notice:
a. Functions as an expand/collapse for the mouse user
b. Menu button isn’t keyboard accessible, doesn’t support aria-expanded
c. Items in the sidebar are visually hidden but not programmatically hidden; keyboard user can tab to hidden / collapsed items

Expected behavior
Hamburger menu icon should present a menu that contains same menu items as are seen in desktop OR element should be represented as a simple show/hide for a collapsed sidebar, and when the sidebar is collapsed its elements shouldn't be able to take keyboard focus because they're not visible

Screenshots

Desktop:
This issue is not OS or browser specific, but for tracking purposes, testing was done on Win11, in Edge Version 114.0.1823.58 (Official build) (64-bit), and the screenreader in use was the common 3rd party screenreader NVDA (http://www.nvaccess.org).

Smartphone:
This issue is not device, OS, or browser specific.

Additional context
This is an accessibility issue, please annotate this bug with the 'accessibility' label.

[fstrr]

This is an issue with the Read The Docs platform.