MPDF set columns - Columns height

I am using mpdf for generating PDF and used setColumns() for set the pdf columns. But it split as 2 columns for minimal data. It's in landscape mode and I need to cover the 2nd column after cover (full) the first column. Is there any way for this?

Current view

code

require_once Yii::getPathOfAlias('application.vendors.MPDF.mpdf') . '.php';
        $mpdf = new mPDF('c', 'A4-L');


        $stylesheet = file_get_contents(Yii::getPathOfAlias('application.modules.examination.views.result.gradecard').'.css');
        $mpdf->WriteHTML($stylesheet, 1);         
        $mpdf->SetColumns(2);
        $mpdf->WriteHTML($this->renderPartial('grade_pdf2', array(), true));           
        $mpdf->Output();