Edge Open
It grows out of the edge nearest the trigger, not out of its own middle. The transform-origin is what carries the relationship; without it the card looks unrelated to what opened it.
Usage
Meant for
Examples
On a Hover Card
Point at @alina. A hover card rising from the element it belongs to, after a 300 ms wait for intent. Slower in and faster out than a popover — it was not asked for, so it should not arrive like a click. The card is HoverCardContent's surface, 288 wide.
The class is wm wm-edge-open — the first half is the marker the trigger and reduced-motion rules hook into, the second is the effect.