Use it on attributes or class names, set & unset them using JS, but please, use the given names for each purpose and document them here.
By default, if no stateful class is defined, the default state of the movement should be the off-screen waiting for a trigger to start.
Set: Starts the animation to the on-screen state Unset: Rollback the animation to the off-screen state
Set: Starts the animation to the off-screen state Unset: Rollback the animation to the on-screen state