Adding the compatibility notice via JavaScript prevents the
`meta description` Sphinx extension from taking the notice
as part of the description.
This also changes the redirect URL to point to the page the user
is currently reading instead of always pointing to the homepage.
instant.page prefetches pages when the user hovers links for
more than 65 milliseconds. This can be used to make navigation feel
significantly faster.
Note that this will have no effect in Firefox when using uBlock Origin,
as it forcibly disables prefetching.
The search bar will now behave in a "sticky" manner. This makes
the logo disappear more smoothly instead of being abruptly hidden.
Another upside is that the drop shadow will only appear once the
search bar is made fixed.
