protected function renderItem($color)
    {
        return Html::tag('div', (
            Html::tag('div', Html::tag('div', '', ['class' => 'circle']), ['class' => 'circle-clipper left'])
            . Html::tag('div', Html::tag('div', '', ['class' => 'circle']), ['class' => 'gap-patch'])
            . Html::tag('div', Html::tag('div', '', ['class' => 'circle']), ['class' => 'circle-clipper right'])
        ), ['class' => 'spinner-layer spinner-' . $color]);
    }