Ester Martí

ALT Our preferred solution is to use <link rel="stylesheet"> for statically extracted styles and plain inline styles for dynamic values. E.g. <div style={{...}}>. You could however build a CSS-in-JS library that extracts static rules into external files using a compiler. That's what we use at Facebook. It's tempting to use dynamically generated style sheets since it contains only the rules that are active on the page right now. However, this comes at a cost. Usually at the expense of runtime cost. It also comes at a cost of inserting new rules frequently which invalidates a lot of the work that has already been done. Shared stylesheets are efficient to parse and are very cacheable. By extracting them into shared styles you are also effectively batching a lot of that work up front. This lets you avoid doing that work later on as the user starts interacting with the page.