Ghost Out
Solid turns to ghost using an inset shadow instead of a border, so nothing shifts by a pixel.
Usage
Meant for
Examples
On a Button
Hover it. Solid turns to outline in 150 ms. The outline is an inset shadow, not a border, so the button does not shift by a pixel as it changes state.
The class is wm wm-ghost-out — the first half is the marker the trigger and reduced-motion rules hook into, the second is the effect.