Pin-point the offset height of an item in a 3-width grid

rowOffsetHeight.dart

void main() {
  int listLength = 24;
  int index = 5;
  int h = (listLength * 66) ~/ 3;
  int col = index % 3;
  print('find index: $index');
  print('gridHeight: $h');
  print('rows      : ${h / 66}');
  print('column    : ${col + 1}');
  print('row height: ${((((index - 1) * 66) / 3) + 88) - (col * 22)}');
}