Constraints

To fully understand Flutter’s layout system, you need
to learn how Flutter positions and sizes
the components in a layout. For more information,
see Understanding constraints.

Videos

The following videos, part of the
Flutter in Focus series,
explain Stateless and Stateful widgets.

Flutter in Focus playlist

Each episode of the
Widget of the Week series
focuses on a widget. Several of them includes layout widgets.

Flutter Widget of the Week playlist

Other resources

The following resources might help when writing layout code.

Layout tutorial
      Learn how to build a layout.

Widget catalog
      Describes many of the widgets available in Flutter.

HTML/CSS Analogs in Flutter
      For those familiar with web programming,
this page maps HTML/CSS functionality to Flutter features.

Flutter Gallery running app, repo