Simplify CSS selectors to comply with coding standards

[ashleykolodziej]

The CSS selectors here are long and difficult for people coding themes to override. Simplifying them shouldn't affect sites or custom sites as long as the HTML doesn't change, since more specific selectors will always override less specific ones. Our coding standards say that no more than three levels of nesting are allowed, and nesting should be avoided at all costs.

Here's an example: https://github.com/bu-ist/bu-slideshow/blob/master/interface/css/bu-slideshow.css#L422

Let's get these cleaned up! 👍