Styling at the Macro level is a bit special, in general Macro's are applied on a page via the RTE, but they can also be used in the Global Layout, Page Layout, Blog Post Layout and so on, the reason is that changing it is quite easy via Confluence Administration -> General Configuration -> User Macros - So we dont have to mess around in the layouts, which can be a bit risky.
A macro can be from a very simple style containing only something like:
## @noparams
<style><!--
div\#renderChildren { visibility:hidden;display:none; }
--></style>
to a large macro containing someting like a complete footer, se my footer here