Changing colors of single column in stacked bar chart

I am trying to highlight a single set of values in a c3.js stacked bar chart. Following [this example](http://jsfiddle.net/JedRW/1/) I can change the color of a single bar in a non-stacked bar, but I can't figure out how to identify the indexes of a single stack. Here is a [jsfiddle](https://jsfiddle.net/vabm/kmjpg30c/1/) of my work-in-progress. How can I get the indexes of the 3 values of a single stack and then use them to change their colors? For example, if I want to highlight "2ND" by changing the colors to a set of reds? Cheers!!