CSS Modules

You create a ".module.css" file in the same folder as your component.
This uses className but the CSS is scoped to the component.
React will generate a specific unique class for each rendered component and assign the CSS to that class.

button.module.css

.button { 
   background-color : 'red';  
} 

button.jsx

import style from 'button.module.css'  

const Button = () => { 
   return <button className = { style.button } >My Button</button>