function ColorDarken($color, $dif=20){
     
        $color = str_replace('#', '', $color);
        if (strlen($color) != 6){ return '000000'; }
        $rgb = '';
     
        for ($x=0;$x<3;$x++){
            $c = hexdec(substr($color,(2*$x),2)) - $dif;
            $c = ($c < 0) ? 0 : dechex($c);
            $rgb .= (strlen($c) < 2) ? '0'.$c : $c;
        }
     
        return '#'.$rgb;
    }