Color fading code according to Unix time

What I have here is a silly piece of code. Why is it silly? I know little to nothing about programming, It ought to be silly!

$currentt = time();
echo $info_message;
if (count($u_ids))
{
echo "$w_search_results<br>";
echo "<table>";
for ($i=0;$i<count($u_ids);$i++)
{
echo "<tr><td><a href=\"fullinfo.php?user_id=".$u_ids[$i]."&session=$session\">".$u_names[$i]."</a></td> <td>\n";
$diffe = $currentt - $last_visit[$i];
if ($diffe < 1000000)
echo "<font color=00ffff>";
else if ($diffe < 2000000)
echo "<font color=00eeee>";
else if ($diffe < 3000000)
echo "<font color=00dddd>";
else if ($diffe < 4000000)
echo "<font color=00cccc>";
else if ($diffe < 5000000)
echo "<font color=00bbbb>";
else if ($diffe < 6000000)
echo "<font color=00aaaa>";
else if ($diffe < 7000000)
echo "<font color=009999>";
else if ($diffe < 8000000)
echo "<font color=008888>";
else if ($diffe < 9000000)
echo "<font color=007777>";
else
echo "<font color=006666>";
print "Last Visited: <font face=Courier>" . date("M-d-Y H:i:s ", $last_visit[$i]);


What I'm trying to do here, is to make the color of the text go from brightest to dimest according to the last time they visit. $last visit respersent the unix time code of the last time they log in, and this code basically output everyone's name and the time they login.

How do I improve on this? Surely I want more color shade then the number if IF statment allow, but thinking about how to translate the $diffe, as in the number of seconds between now and the last time they login, into a proper format that font color will use, is giving me a hard time.

Sorry if this seem beginner, but I have no PHP courses and other programming courses. Just want to start impoving code and learn from there.

Thank you in advance for your advice!

hth, you can mess with the initial parameters to fine tune the effect:


$smallest['timediff'] = 1000000;
$smallest['shade'] = 'ff'; // just one block (dec 0-255)
$largest['timediff'] = 9000000;
$largest['shade'] = '66';

// loop is just to demonstrate, you still want to calculate the diff the way you do now.
for ($diff = $smallest['timediff']; $diff <= $largest['timediff']; $diff += mt_rand(0, 100000))
{
if ($diff <= $smallest['timediff'])
{
$shade = '#00' . str_repeat($smallest['shade'], 2);
}
else if ($diff >= $largest['timediff'])
{
$shade = '#00' . str_repeat($largest['shade'], 2);
}
else
{
// the difference expressed as a percentage of the time interval
$per = (($diff - $smallest['timediff']) * 100)/($largest['timediff'] - $smallest['timediff']);
// the color interval
$shadediff = hexdec($largest['shade']) - hexdec($smallest['shade']);
// the smallest color + the percentage of the color interval equivalent to the percentage of the time interval
$shade = '#00' . str_repeat(dechex(hexdec($smallest['shade']) + ($shadediff * $per / 100)), 2);
}
echo '<span style="color: ' . $shade . ';">' . $shade . '</span><br />';
}