anchor.diff:        ..classes.add('Paper');
   
       shadowElement.classes.add('Paper_shadow');
  -    element.append(shadowElement);
  +
  +    element
  +      ..append(shadowElement);
     }
   
     v.VRootDecorator<html.DivElement> build() =>
  
positive.code: 
  class PaperStyleSheet extends css.StyleSheet {
    build() => [
        css.rule('.Paper_shadow', [
          css.position('absolute'),
          css.top(0),
          css.left(0),
          css.right(0),
          css.bottom(0),
          css.borderRadius('inherit'),
          css.transition('box-shadow 0.5s $swiftEaseInOut'),
        ]),
  
        css.rule('.Paper', [
          css.rule('&.round', [
            css.borderRadius('3px')
          ]),
          css.rule('&.circle', [
            css.borderRadius('50%')
          ]),
  
negative.code:         css.rule('&.z5 > .Paper_shadow', [
            paperShadow(5)
          ])
        ]),
  
        css.rule('.Paper_shadow', [
          css.position('absolute'),
          css.top(0),
          css.right(0),
          css.bottom(0),
          css.left(0),
          css.borderRadius('inherit'),
          css.transition('box-shadow 0.5s $swiftEaseInOut'),
        ])
      ];
  }
  