Looking at the CSS using the browser dev tools, I see CSS variables like `--tw-border-spacing-x` which indicates to me that this is indeed using Tailwind. I've never tried Tailwind UI myself so I'm not sure if it's just Tailwind or Tailwind UI.
yes, tailwindUI is
my bet is that shadcn UI will be next
Bootstrap had a ton of defaults, but Tailwind doesn't come with any, but it makes it easy for designers to make a site look just like any other, but that's not a requirement
you’re correct, it’s tailwindcss but not tailwind ui