Color.php

<?php

$colors = array();

for ($i = 0; $i <= 256; $i++) {
	$colors[] = $i;
}

?>

<ul style="list-style: none; width: 900px; margin: 0 auto; padding: 0;">
<?php
foreach ($colors as $color) :
	$bekgron = 'rgb('.$color.', '.$color.', '.$color.')';
	$text = ($color < 128 ? '#fff' : '#000');
?>
	<li style="width: 148px; float: left; display: inline-block; border: 1px solid <?php echo $text ?>;">
		<span style="line-height: 1.8em; width: 100%; text-align: center; color: <?php echo $text ?>; display: block; background: <?php echo $bekgron ?>"><?php echo $bekgron ?></span>
	</li>
<?php endforeach ?>
</ul>