anchor.diff:  
     @override
     Widget build(BuildContext context) {
  +    final ColorScheme colorScheme = Theme.of(context).colorScheme;
  +
       return SafeArea(
         top: false,
         bottom: false,
  
positive.code:                   onTap: () {
                      print('Card was tapped');
                    },
                    splashColor: Theme.of(context).colorScheme.primary.withAlpha(30),
                    child: TravelDestinationContent(destination: destination),
                  ),
                ),
  
negative.code:                       _isSelected = !_isSelected;
                      });
                    },
                    // Generally, material cards use onSurface with 12% opacity for the pressed state.
                    splashColor: colorScheme.onSurface.withOpacity(0.12),
                    // Generally, material cards do not have a highlight overlay.
                    highlightColor: Colors.transparent,
                    child: Stack(
                      children: <Widget>[
                        Container(
                          color: _isSelected
                            // Generally, material cards use primary with 8% opacity for the selected state.
                            // See: https://material.io/design/interaction/states.html#anatomy
                            ? colorScheme.primary.withOpacity(0.08)
                            : Colors.transparent,
                        ),
                        TravelDestinationContent(destination: widget.destination),
                        Align(
                          alignment: Alignment.topRight,
                          child: Padding(
                            padding: const EdgeInsets.all(8.0),
                            child: Icon(
                              Icons.check_circle,
                              color: _isSelected ? colorScheme.primary : Colors.transparent,
                            ),
                          )
                        ),
                      ],
                    ),
                  ),
                ),
              ),
  