In reference to #572 – adds .group-option-[index] classes to optgroup options & choices, e.g. "group-option-1"
Add .group-option-[i] classes to optgroup options and choices
Adding CSS styles based on an index is pretty brittle - all it takes is a new data point to break an entire list of styles. I think a more solid approach would be to simply carry over any styles from an optgroup to the respective output in Chosen.
Thanks anyways, @camerond