lid;
  margin-right: 20px;
  margin-bottom: 30px;
  color: green;
  box-shadow: 10px 30px 10px 30px black;
}
.expected {
  margin-right: 40px;
}
</style>
<body>
<script>
test_interpolation({
  property: 'box-shadow',
  from: neutralKeyframe,
  to: '20px 20px 20px 20px black',
}, [
  {at: -0.3, expect: 'rgb(0, 0, 0) 7px 33px 7px 33px'},
  {at: 0, expect: 'rgb(0, 0, 0) 10px 30px 10px 30px'},
  {at: 0.3, expect: 'rgb(0, 0, 0) 13px 27px 13px 27px'},
  {at: 0.6, expect: 'rgb(0, 0, 0) 16px 24px 16px 24px'},
  {at