That's a holdover of the project from which I extracted these, reachably. We decided to use snake case across html css and javascript to keep things standard - feel free to judge that decision.
Given that people will most likely be using this in more traditionally camel cased situations, I think I will go through and change that this weekend. Thanks for pointing that out!
Please keep the snake_case. Think of all the things that CoffeeScript borrowed from ruby while omitting the snake_case. We aren't that far from being able to write most frontend code with snake_case. All it would take is a Backbone fork and a jQuery wrapper to get us most of the way there!
Interesting perspective! I agree, but think the majority of people prefer semantics by language.