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;
}