How to make React CSS import component-scoped?

It sounds like CSS Modules, or many of the other CSS-in-JS packages, does what you want. Others include Emotion (my current favorite), Styled Components, or many of the packages here.

A CSS Module is a CSS file in which all class names and animation names are scoped locally by default. All URLs (url(…)) and @imports are in module request format (./xxx and ../xxx means relative, xxx and xxx/yyy means in modules folder, i. e. in node_modules).

Here’s a quick example:

Let’s say we have a React component like:

import React from 'react';
import styles from './styles/button.css';

class Button extends React.Component {
  render() {
    return (
      <button className={styles.button}>
        Click Me
      </button>
    );
  }
}
export default Button;

and some CSS in ./styles/button.css of:

.button {
  border-radius: 3px;
  background-color: green;
  color: white;
}

After CSS Modules performs it’s magic the generated CSS will be something like:

.button_3GjDE {
  border-radius: 3px;
  background-color: green;
  color: white;
}

where the _3DjDE is a randomly generated hash – giving the CSS class a unique name.

An Alternative

A simpler alternative would be to avoid using generic selectors (like p, code, etc) and adopt a class-based naming convention for components and elements. Even a convention like BEM would help in preventing the conflicts you’re encountering.

Applying this to your example, you might go with:

.aboutContainer {
  # Some style
}

.aboutContainer__code {
  # Some style
}

Essentially all elements you need to style would receive a unique classname.