Update: you can now load folders on certain pages using conditions. Some users may prefer that to using the body class method explained below.
You can define a subset of posts or pages that should have the same styling by adding custom classes to posts or pages, and then instructing Microthemer to prefix the selectors it generates with those classes. This essentially means that you can tie a set of styles to a class, and then add that class to another page to apply the styling.
Microthemer will also pick up body classes your theme adds, like post categories, types, or user access status.