anchor.diff:          builder: (BuildContext context, BoxConstraints constraints) {
             final Size size = constraints.biggest;
             final double appBarHeight = size.height - statusBarHeight;
  -          final double extraPadding = new Tween<double>(begin: 10.0, end: 24.0).lerp(
  -            ((appBarHeight - kToolbarHeight) / _kAppBarHeight).clamp(0.0, 1.0)
  -          );
  +          final double t = (appBarHeight - kToolbarHeight) / (_kAppBarHeight - kToolbarHeight);
  +          final double extraPadding = new Tween<double>(begin: 10.0, end: 24.0).lerp(t);
             final double logoHeight = appBarHeight - 1.5 * extraPadding;
             return new Padding(
               padding: new EdgeInsets.only(
  
positive.code:               bottom: extraPadding
              ),
              child: new Center(
                child: new PestoLogo(showText: appBarHeight >= 70.0, height: logoHeight)
              )
            );
          }
  
negative.code: }
  
  class PestoLogo extends StatefulWidget {
    PestoLogo({this.height, this.t});
  
    final double height;
    final double t;
  
    @override
    _PestoLogoState createState() => new _PestoLogoState();
  