In November 2014, Christopher "vjeux" Chedeau(new tab), who is working on React(new tab) and React Native(new tab) at Facebook, gave a thought-provoking talk titled "CSS in JS"(new tab). He outlined the problems of CSS at scale and later showed how they solved those at Facebook. They were able to solve most, but in return had to add a lot of additional tooling.

Then he introduced a complete new approach to handle those issues without any actual extra work. Using inline styles. It seemed crazy, but just worked magically.

To make a long story short, soon after the talk, dozens of libraries grew on Github. Most of them were built directly for React while others were more open.
For a quick overview, check out Michele Bertoli(new tab)'s great css-in-js(new tab) repository.

Fela's creator, Robin Weser(new tab), also published a solution called react-look(new tab) himself. It was nicely accepted by the community and grew to a proud number of 550 stars at the time of writing this article.
Still he noticed that with each new feature and different use-case it would get more and more complicated to handle all the different components. He found that one of the major problems was the deep binding to React itself as well as the approach to satisfy every single use-case by providing numerous configuration options and several APIs.

After a long period of research and a lot gained experience with CSS in JS techniques, he created a whole new approach which became the library we now know as Fela.

Like many powerful and widely adopted libaries such as React(new tab) or Redux(new tab), Fela does not explicitly tell you how to write your styles, but rather gives you some nice and simple APIs to help you build your styling environment.


There is one important feature of react-look which turned out to be really useful in real applications: dynamic styling. There it seems quite logical that Fela is designed to be dynamic by default.

Despite many benefical side effects, Fela actually only has three major goals.

  1. Make styling dynamic by default
  2. Be framework-agnostic, that is being used with any view library
  3. Be high performant

Read about the principles to understand how and why Fela is dynamic by default.