one nice thing about placeholders is that they are super easy to globally find+replace - wondering if something like `%pointer` or `%clickable` would help make it more clear what the placeholder is adding - 'personality' is ambiguous enough that people will need to refer back to the style block to know what's going on.

if we don't want to pair it too strongly with button elements, I'm wondering if we could put it in `_modifiers` with an identically-named class (e.g. `.clickable`), or in an `_interactions` partial that had other hover/click-related styles. That would require a bit more planning, but it would help users know where to look for things of interest.

BTW, a lot of my thinking about 'good' Sass framework organization comes from [Foundation](http://foundation.zurb.com/docs/index.html) ([git](https://github.com/zurb/foundation/tree/master/scss/foundation)), Bootstrap ([git](https://github.com/twbs/bootstrap/tree/master/less), and the framework we built at my last job, Fred ([git](https://github.com/springload/Fred.scss/tree/master/scss)) - these have gone through many iterations to make them accessible to new devs and I think they have pretty strong conceptual organization given the constraints (with the possible exception of Bootstrap - it's pretty flat).