anchor.diff:          new AnimatedCrossFade(
             firstChild: new Container(height: 0.0),
             secondChild: new Container(
  -            margin: const EdgeInsets.only(
  -              left: 60.0,
  -              right: 24.0,
  +            margin: const EdgeInsetsDirectional.only(
  +              start: 60.0,
  +              end: 24.0,
                 bottom: 24.0,
               ),
               child: new Column(
  
positive.code:               child: const Text('CONTINUE'),
              ),
              new Container(
                margin: const EdgeInsets.only(left: 8.0),
                child: new FlatButton(
                  onPressed: widget.onStepCancel,
                  textColor: cancelColor,
  
negative.code:             ]
            ),
            new Container(
              margin: const EdgeInsetsDirectional.only(start: 12.0),
              child: _buildHeaderText(index)
            )
          ]
  