I am about to develop a Tizen web app (Basically a Single Page Application that will be executed locally like Electron or Ionic apps) using react js.

What I want to do is let users submit their custom themes so others can use them. It's like VS Code themes mechanism basically. I want my app to load the styling values (color, radius, shadow, ...) from a JSON file.

Let's say that my app already loaded the JSON file but what is the best way to assign the variables. I know that I can use className like in react-native but for react-dom inline style is not the best way.

I found a package called css-in-js but is there a better "cleaner" solution?

PS: Based on Samsung Smart TV SPECIFICATIONS custom variables are not supported on all devices.