<!DOCTYPE html>
<html>
<body>

<?php
$t=date("H");
if ($t<"10")
   {
   echo "Have a good morning!";
   }
elseif ($t<"20")
   {
   echo "Have a good day!";
   }
else
   {
   echo "Have a good night!";
   }
?>

</body>
</html>