macgyer\yii2materializecss\widgets\Breadcrumbs::init PHP Method

    public function init()
    {
        if (!isset($this->containerOptions['class'])) {
            Html::addCssClass($this->containerOptions, ['breadcrumbsContainer' => 'breadcrumbs']);
        }
        if (!isset($this->options['class'])) {
            Html::addCssClass($this->options, ['wrapper' => 'nav-wrapper']);
        }
        if ($this->innerContainerOptions !== false && !isset($this->innerContainerOptions['class'])) {
            Html::addCssClass($this->innerContainerOptions, ['innerContainer' => 'col s12']);
        }
    }