let height = ...
let bottomSpace = ...

<Spring
  from={{
    height: 0,
    bottom: '100%',
    marginBottom: 0
  }}
  to={{
    height: height,
    bottom: '100%',
    marginBottom: bottomSpace
  }}
>
  {styles => <animated.div style={styles} className="mc-gee"></animated.div>}
</Spring>