I use `ReactDOM.unstable_renderSubtreeIntoContainer` to render a portal.

``` javascript
class Modal extends React.Component {

componentDidMount() {
    this.node = document.createElement('div');
    document.body.appendChild(this.node);
    this.renderPortal(this.props);
}

componentWillReceiveProps(nextProps) {
    this.renderPortal(nextProps);
}

componentWillUnmount() {
    ReactDOM.unmountComponentAtNode(this.node);
    document.body.removeChild(this.node);
}

renderPortal = (props) => {
    renderSubtreeIntoContainer(this, <ModalPortal {...props} />, this.node);
}

render() {
    return null;
  }
}
```

In my root component:

``` javascript
class App extends React.Component {
    static childContextTypes = {
        highlightColor: React.PropTypes.object
    }

    getChildContext() {
        return {
            highlightColor: this.props.highlightColor
        }
    }

    ...
}
```

The context of root component will be updated and passed to children if  `this.props.highlightColor` is changed. This is right.
I can access the correct context in the `<ModalPortal/>` component in the first render.
And after that the context passed to  `<ModalPortal/>` **does not change any more** when the context of root component changed.
But I can access the correct context in the `<Modal/>`  every render.

what's wrong with my code ?

normalizedMarkup.substring(diffIndex - 20, diffIndex + 20) +
          '\n (server) ' + rootMarkup.substring(diffIndex - 20, diffIndex + 20);
        invariant(
          container.nodeType !== DOC_NODE_TYPE,
          'You\'re trying to render a component to the document using ' +
          'server rendering but the checksum was invalid. This usually ' +
          'means you rendered a different component type or props on ' +
          'the client from the one on the server, or your render() ' +
          'methods are impure. React cannot handle this case due to ' +
          'cross-browser quirks by rendering at the document root. You ' +
          'should look for environment dependent code in your components ' +
          'and ensure the props are the same client and server side:\n%s',
          difference
        );
        if (__DEV__) {
          warning(
            false,
            'React attempted to reuse markup in a container but the ' +
            'checksum was invalid. This generally means that you are ' +
            'using server rendering and the markup generated on the ' +
            'server was not what the client was expecting. React injected ' +
            'new markup to compensate which works but you have lost many ' +
            'of the benefits of server rendering. Instead, figure out ' +
            'why the markup being generated is different on the client ' +
            'or server:\n%s',
            difference
          );
        }
      }
    }