echo Html::errorSummary($model, ['header' => 'Please correct the following']);
echo Html::errorSummary($model, ['header' => 'Please correct the following', 'class' => 'alert alert-danger']);This code example displays the error summary with a custom CSS class name. The `class` parameter sets the CSS class name for the error summary. Package Library: Yii2 Framework (built-in feature of Yii2).