anchor.diff:      final textTheme = Theme.of(context).textTheme;
       final colorScheme = Theme.of(context).colorScheme;
   
  -    return Container(
  -      padding: const EdgeInsetsDirectional.only(
  -        start: 24,
  -        top: 12,
  -        end: 24,
  -        bottom: 32,
  -      ),
  -      constraints: BoxConstraints(maxHeight: maxHeight),
  -      child: SingleChildScrollView(
  -        child: Column(
  -          crossAxisAlignment: CrossAxisAlignment.start,
  -          mainAxisSize: MainAxisSize.min,
  -          children: [
  -            Text(
  -              title,
  -              style: textTheme.display1.apply(
  -                color: colorScheme.onSurface,
  -                fontSizeDelta:
  -                    isDisplayDesktop(context) ? desktopDisplay1FontDelta : 0,
  -              ),
  -            ),
  -            SizedBox(height: 12),
  -            Text(
  -              description,
  -              style: textTheme.body1.apply(color: colorScheme.onSurface),
  -            ),
  -          ],
  +    return Align(
  +      alignment: AlignmentDirectional.topStart,
  +      child: Container(
  +        padding: const EdgeInsetsDirectional.only(
  +          start: 24,
  +          top: 12,
  +          end: 24,
  +          bottom: 32,
  +        ),
  +        constraints: BoxConstraints(maxHeight: maxHeight, maxWidth: maxWidth),
  +        child: SingleChildScrollView(
  +          child: Column(
  +            crossAxisAlignment: CrossAxisAlignment.start,
  +            mainAxisSize: MainAxisSize.min,
  +            children: [
  +              Text(
  +                title,
  +                style: textTheme.display1.apply(
  +                  color: colorScheme.onSurface,
  +                  fontSizeDelta:
  +                      isDisplayDesktop(context) ? desktopDisplay1FontDelta : 0,
  +                ),
  +              ),
  +              SizedBox(height: 12),
  +              Text(
  +                description,
  +                style: textTheme.body1.apply(color: colorScheme.onSurface),
  +              ),
  +            ],
  +          ),
           ),
         ),
       );
  
positive.code:       buildRoute: _currentConfig.buildRoute,
      );
      if (isDesktop) {
        // If the available width is not very wide, reduce the amount of space
        // between the demo content and the selected section.
        const reducedMiddleSpaceWidth = 48.0;
  
        // Width of the space between the section and the demo content
        // when the code is NOT displayed.
        final nonCodePageMiddleSpaceWidth = mediaQuery.size.width > 900
            ? horizontalPadding
            : reducedMiddleSpaceWidth;
  
        // Width of the space between the section and the demo content
        // when the code is displayed.
        final codePageMiddleSpaceWidth =
            min(reducedMiddleSpaceWidth, nonCodePageMiddleSpaceWidth);
  
        // Width of the space between the section and the demo content
        final middleSpaceWidth = _state == _DemoState.code
            ? codePageMiddleSpaceWidth
            : nonCodePageMiddleSpaceWidth;
  
        // Width for demo content.
        // It is calculated in this way because the code demands more space.
        final demoContentWidth = (mediaQuery.size.width -
                horizontalPadding * 2 -
                nonCodePageMiddleSpaceWidth) /
            2;
  
        final Widget sectionAndDemo = (_state == _DemoState.fullscreen)
            ? demoContent
            : Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Expanded(child: section),
                  SizedBox(width: middleSpaceWidth),
                  Container(
                    width: demoContentWidth,
                    child: demoContent,
                  ),
                ],
              );
  
        body = SafeArea(
          child: Padding(
  
negative.code:   const _DemoSectionOptions({
      Key key,
      this.maxHeight,
      this.maxWidth,
      this.configurations,
      this.configIndex,
      this.onConfigChanged,
    }) : super(key: key);
  
    final double maxHeight;
    final double maxWidth;
    final List<GalleryDemoConfiguration> configurations;
    final int configIndex;
    final ValueChanged<int> onConfigChanged;
  