Provide an alternative style for references to work in more of a pop-up way

A work in progress using the default html dialog element as a basis:

Added some further steps to the issue summary as TODOs

1. Handle close on click outside
2. Add default styling for sliding up from the bottom

JS overrides for animation & slide up from bottom, including respecting prefers-reduced-motion for accessibility added

Hi,
I tested the footnote 4.0dev plus #10 and it worked.
thanks!

Thanks for confirming, merged; will create a new release soon

Automatically closed - issue fixed for 2 weeks with no activity.