Shake.
A short sideways nudge signals a rejected action.
See the movement
One intentional triggerPlayback starts only when you request it. Stop returns to the still illustration.
What it does
A restrained horizontal shake can reinforce a validation failure. It must accompany a readable explanation, since motion alone cannot communicate what went wrong or how to fix it.
Timing curve
ease-in-outDefault duration450ms
RepetitionOnce per trigger
Make the motion useful
Choose an effect that supports the component’s purpose. Keep the final state clear, preserve focus and reading order, and pair important feedback with a visible message.
CSS animation reference