protected function getDataCss($variable)
    {
        $css = [
            'padding'               => '7px',
            'background-color'      => $this->zebra ? '#D8D9DB' : '#FFF',
            'color'                 => '#405261',
        ];

        $type = gettype($variable);
        if ($type == 'NULL') {
            $css['color'] = '#999';
        }

        return $this->arrayToCss($css);
    }