#occurrence {
  marker-width: 3.45;
  marker-line-width: 0;
  marker-allow-overlap: true;
  marker-fill: #C06719;
  marker-comp-op: screen;

  [zoom >= 11] { marker-width:  3.45; }
  [zoom >= 12] { marker-width:  6.25; }
  [zoom >= 13] { marker-width:  9.88; }
  [zoom >= 14] { marker-width:  15.63; }
  [zoom >= 15] { marker-width:  24.71; }
}
