Here's some code that should do it:
<?php
list ($y, $m, $d) = explode (date ('Y-n-j'));
$start = 1;
$end = date ('t');
for ($i = $start; $i <= $end; $i++) {
if ($i < $d) {
// before
printf ('<td class="before">%s</td>', $i);
} elseif ($i == $d) {
// today
printf ('<td class="today">%s</td>', $i);
} else {
// after
printf ('<td>%s</td>', $i);
}
}
?>
Then you can style it to suite your needs, ie:
<style type="text/css">
td {
background-color: #fff;
}
td.before {
background-color: #eee;
}
td.today {
background-color: #ddd;
font-weight: bold;
}
</style>
Hope this helps.
Cheers,
Lux