myElements.less

.super-element {
  &__inner-stuff {
    width: 69px;
  }
  
  @media screen and (max-width: 760px;) {
    &__farts {
      height: 10px;
    }
  }
}

.whatever-element {
  content: 'you-get-the-picture-by-now...';
}

super-element.jsx

import React from 'react';
importCss myElements from 'myElements.less';
 
class SuperElement extends React.Component {
    constructor(props) {
        super(props);
    }
 
    render() {
        return (
            <super-element className={myElements.superElement}>
              whatever
            </super-element>
        );
    }
}
 
export default SuperElement;