You might be on the fence with CSS-in-JS — especially after hearing from Rich Harris about Svelte on The Changelog #332. Max Stoiber writing on his personal blog with his take on the matter:
Primarily, CSS-in-JS boosts my confidence. I can add, change and delete CSS without any unexpected consequences. My changes to the styling of a component will not affect anything else. If I delete a component, I delete its CSS too. No more append-only stylesheets!