cross-fade {
  start: container {
    color {
      color: red;
      bounds: 0 0 10 10;
    }
    color {
      color: green;
      bounds: 10 10 10 10;
    }
  }
  end: color {
    color: blue;
    bounds: 5 5 10 10;
  }
  progress: 0.2;
}