sidebar.js

class Sidebar extends React.Component {   
    // this class will be responsible 
    // for positioning, styles, animations, etc.
    // and that's about it...
    render() {
        const {
            isOpen,
            children,
        } = this.props
        return (
            <div className="some-global-sidebar-class ${isOpen ? '--expanded' : '--closed'}">
                {children}
            <div>
        );
    }
}

sidebar_content_example.js

import Sidebar from 'shared/sidebar'

class MyChildComponent extends React.Component {


    render() {
        return (
          <Sidebar isOpen={true}>
              <div>
                  My Custom Content that fits the
                  constraints provided by <Sidebar/>
              </div>
          <Sidebar/>
        );
    }
}