Content beneath fixed AppBar : <p>Probably a basic question, but I couldn't find any example in the documentation. Using <code>material-ui-next</code> <em>beta.30</em>. I have the following:</p>

<pre><code>import * as React from 'react';
import * as ReactDOM from 'react-dom';
import * as mui from 'material-ui';
import 'typeface-roboto';

function App() {
  return (
    &lt;div&gt;
      &lt;mui.Reboot /&gt;
      &lt;mui.AppBar color="primary" position="fixed"&gt;
        &lt;mui.Toolbar&gt;
          &lt;mui.Typography color="inherit" type="title"&gt;
            My Title
          &lt;/mui.Typography&gt;
        &lt;/mui.Toolbar&gt;
      &lt;/mui.AppBar&gt;
      &lt;mui.Paper&gt;
        My Content
      &lt;/mui.Paper&gt;
    &lt;/div&gt;
  );
}

ReactDOM.render(
  &lt;App /&gt;,
  document.getElementById('container')
);
</code></pre>

<p>And I want the <code>mui.Paper</code> content appear <em>beneath</em> the <em>AppBar</em>, and not hidden by it. Is there a component I'm missing somewhere?</p>
