Back to top button: Default needs to be styled

A back-to-top button that is available by adding the following to the .yml file:
theme:
features:
- navigation.top

However, this needs some tweaking to work for us. Specifically, the default is a light grey button that appears at the top of the page whenever you are scrolling up (it disappears when scrolling down). Ideally it would be at the bottom right of the page and remain there when scrolling up or down. See the one on the new website and try to make it similar for consistency! The default text on the button could also be changed to the icon used on the new website.

After this issue has been resolved, https://github.com/Dyalog/documentation/issues/520 can be done.

Start by locating the stylesheet that controls the navigation.top back-to-top button and compare its current behavior with the button on the new website. Check the .yml configuration mentioned in the issue and issue 520 for integration context; done means the button stays at the bottom right while scrolling, matches the new site's styling, and uses its icon.

Written by the indexing model from the issue text.