Migrate project to use Tailwind CSS instead of Bootstrap #802
Description
This would enable a fresh, modern UI, still with backward support as far as Edge 18. It would mean abandoning IE11, but that doesn't really work as a PWA in any case, since there is no Service Worker in IE11, and therefore it has to run as an online Web app or from the File System, which is barely functional if at all (haven't tested recently).
However, this should be done in two stages. The first would be a "simple" upgrade to Bootstrap 4. This is because that would enable us to migrate to Font Awesome, also used by Tailwind. The second stage -- more complex -- would then be to migrate to Tailwind CSS.