Previous solution that re-purposed the 'hide' class by making it
`!important` had various unintended side-effects where jQuery .show() was
not able to outweight it. Use a separate class to prevent these
interactions.
By appending the tooltips to `document.body`, we can avoid any stacking context issues caused by surrounding element's CSS.
This uses [tippy.js](https://github.com/atomiks/tippyjs) instead of Fomantic popups. We should aim to replace all Fomantic popups with this eventually and then get rid of the Fomantic `popup` module completely.
