That's straightforward enough. But what if my element has several sub-elements and the breakpoint affects them as well? There are different approaches, and I'm never quite sure which one I should be doing.
Or I could do a combination of the two. Neither of them feels particularly great because of the duplication, but I'm not sure there is a perfect answer here. I err a little more on duplicating the media query, as it seems less error-prone than duplicating selectors.