public function getHtml()
  {
    $html = "";

    $table_classes = $this->getTableClasses();

    if($this->table_responsive)
    {
      $html.= "<div class=\"table-responsive\">\n";
    }

    $id_tag = $this->getTagId();

    $html.= "<table {$id_tag} class=\"table {$table_classes}\">\n";

    // table header
    if( isset($this->header) )
    {
        $html.= "\t<thead>\n";
        $html.= $this->header->getHtml();
        $html.= $this->fillWithEmptyCells($this->header, $this->header->getTagRow() );
        $html.= "\t</thead>\n";
    }

    // table data
    if( isset($this->rows))
    {
      $html.= "\t<tbody>\n";
      foreach($this->rows as $row)
      {
        $html.= $row->getHtml();
        $html.= $this->fillWithEmptyCells($row, $row->getTagRow() );
      }
      $html.= "\t</tbody>\n";
    }

    $html.= "</table>\n";

    if($this->table_responsive)
    {
      $html.= "</div>\n";
    }

    return $html;
  }