Styled Components is a library for React that moves CSS styles into the JS code. Depending on how junior the interviewee was, and what tech they were primarily

Styled Components is a library for React that moves CSS styles into the JS code. Depending on how junior the interviewee was, and what tech they were primarily working with, it's possible they never encountered those terms even as they contributed to the code. Or maybe they just pitched themselves as "full stack" when they were really more back end focused. Doesn't seem that far-fetched to me.