Codice PHP:
function ActiveLink($page)
{
     global 
$current;

     if (
$page == $current)
     {
          echo 
'id="current" '
     }

codice:
<li class="headlink"><a <?php ActiveLink('index.php'); ?>href="index.php">Home</a>
<li class="headlink"><a <?php ActiveLink('chi-siamo.php'); ?>href="chi-siamo.php">Chi siamo</a>