recogito-client-core/themes/default/highlights/_highlights.scss

.r6o-annotation {
  background-color:rgba(255, 165, 0, 0.2);
  border-bottom:2px solid orange;
  cursor:pointer;
}

.r6o-selection {
  background-color:rgba(207, 207, 255, 0.63);
  cursor:pointer;
}