The menu uses the same godui-popover-in keyframe as Popover. Radix publishes the point nearest the trigger as --radix-dropdown-menu-content-transform-origin, so the scale grows from there, and the per-side --godui-enter-x/y variables make it drift 4px out of the trigger.

DropdownMenuSubContent carries the same classes. A sub-menu opening to the right has data-side="right", so it grows out of its parent item, leftmost edge first.

Radix mounts ItemIndicator only while its item is checked, so a keyframe on the indicator plays when the check appears. But the menu's items mount every time it opens, and an already-checked item would pop on each open. So the keyframe is gated on the item's data-animate, which the item sets only once its checked value changes: opening the menu shows the checks still, and a toggle while it's open pops. The keyframe also requires the indicator's own data-state="checked". Radix's Presence keeps an unchecked indicator mounted while it has an animation to finish, so a keyframe that appeared in the same commit as the uncheck would re-pop the check before it vanished.

The indicator reuses godui-fade-scale-in and overrides the start scale locally with --godui-enter-scale: 0.5, so the check grows from half size instead of the 96% a dialog uses. The keyframe still multiplies by the root-only --godui-motion, so reduced motion turns it back into a fade.

Open the menu and toggle the checkboxes and radio items. These items call event.preventDefault() in onSelect, so the menu stays open and you can watch each indicator pop.