Probably not the right issue to comment this in, since it looks like this diff wraps up a bunch of different commits, but:

We might want to be more consistent with prefixing using an `_` or with camelCasing Sass variables. :neckbeard: 

https://github.com/meetup/ui_dev/blob/master/SASS.md#sass-variables-extends-placeholder-selectors-and-mixins