Context Navigation

Changes between Initial Version and Version 1 of Ticket #31354, comment 31

initial	v1
3	3	The `aria-live` announcement isn't needed, in my opinion; it would just make things more verbose. If the change was made to something that preceded the current position in the DOM, it might be necessary, but since the change is to items that follow in the DOM, I think it's fine as is.
4	4
	5	Edit: and I also added the `disabled` attribute in PHP, so it would apply without JS.
5	6	Also changed the CSS & HTML so to reuse the styles from the Reading options screen, updated the function comments to better describe what the added JS now does, and removed the styles that impacted the label design. It's generally considered acceptable for a disabled input to be below color contrast guidelines, but the label still needs to be visible.
6	7