         if not list?
             list = []
         # don't use ListGroup & ListGroupItem with onClick, because then there are div/buttons (instead of ul/li) and layout is f'up
-        <ul className='list-group' ref="list_#{level}">
+        <ul className={'list-group'} ref={"list_#{level}"}>
         {
             list.map (name, idx) =>
                 click  = @category_selection.bind(@, level, idx)

        if not @props.data?
            <Row key='top'>
                <Col sm={8} smOffset={4}>
                    <ul className='list-group'>
                        <li></li><li></li>
                        <li><Loading /></li>
                    </ul>

    render_bottom: ->
        <Row key='bottom'>
            <Col sm={6}>
                <pre ref={'code'} className={'code'}>{@props.code}</pre>
            </Col>
            <Col sm={6}>
                <Panel ref={'descr'} className={'webapp-examples-descr'}>
                    <Markdown value={@props.descr} />
                </Panel>
            </Col>
