t',
  addFrom: 'min-content', /* min-content is 50px, fit-content is ignored
                             because min-content and fit-content are not
                             compatible */
  addTo: '200px', /* combines with fit-content (50px) to be 250px */
  /* the composited from value is a min-content size and the composited
     to value is a fit-content size, so they cannot be interpolated,
     and the animation is discrete */
}, [
  {at: -0.3, expect: '50px'},
  {at: 0, expect: '50px'},
  {at: 0.