Comment by _greim_

Since the goal is to create an illusion of real physics, I wonder when they'll just cut to the chase and start using actual physics engines.

Reason I mention it is neither this nor bezier curves deal with the target changing mid-animation very well. CSS just starts over from the current position, which breaks the illusion. A physics engine would maintain the illusion, and could be simpler to specify:

    transition: physics(system=gravity, force=10, bounce=on, dampening=3)
    transition: physics(system=spring, force=5, bounce=off, dampening=5)