edge { arrowstyle: filled; }
graph {
  colorscheme: x11;
  flow: south;
}
group {
  align: center;
  fill: inherit;
}

[ A ] { color: red; }
[ B ] { color: #ffff99; }
[ C ] { color: #ff0000; }

( cluster_1
  [ A ]
  [ B ]
) { border: dashed  #ff0000; }

[ A ] --> { color: #ff0000ff; } [ B ]
[ B ] --> { color: hsv(1.0,1.0,1.0); } [ C ]
