/** * Renders collapsible toggle button. * @return string the rendering toggle button. */ protected function renderToggleButton() { $bar = Html::tag('span', '', ['class' => 'icon-bar']); $screenReader = "<span class=\"sr-only\">{$this->screenReaderToggleText}</span>"; return Html::button("{$screenReader}\n{$bar}\n{$bar}\n{$bar}", ['class' => 'navbar-toggle', 'data-toggle' => 'collapse', 'data-target' => "#{$this->containerOptions['id']}"]); }