Demo `origin-[top_center]` and other references

I'm perusing the demo here and trying to adapt some of the examples. I'm noticing there's reference to origin-[top_center] in the Navigation Menu demo:

tailwindcss-radix/demo/components/navigation-menu.tsx

Line 148 in 9a222a5

"origin-[top_center] transition-[width_height] duration-300 ease-[ease]"

but I don't see where that variant has been added. I did a full search of the repo on both branches without much luck.

Implementing the demo as is, the menu is centered with respect to the parent element, and is missing the small caret that connects the flyout to the nav. Would appreciate any insight here!

Edit: I'm an actual idiot. It's Friday. Don't hate me. I'm now remembering the [ ] syntax in Tailwind.