carto instances with marker example

instances.css

#crashes_2007_2009_intensity {
  first/marker-fill:#2136E8;
  first/marker-width: 100;
  first/marker-opacity: 0.01;
  first/marker-line-width: 0;
  first/marker-allow-overlap: true;
  second/marker-fill:#17ACCE;
  second/marker-width: 50;
  second/marker-opacity: 0.01;
  second/marker-line-width: 0;
  second/marker-allow-overlap: true;
  green/marker-fill: #11ff66;
  green/marker-opacity: 0.1;
  green/marker-width:20;
  green/marker-line-width: 0;
  green/marker-allow-overlap: true;
  green/marker-comp-op:difference;
}