Instead of doing a class, why not just change the block's style.display attribute? You can change it from block (to show it) and none (to hide it).
This will also get rid of the space it takes up when visible.
So try this and see if it works:
Code:
<script type="text/javascript">
function unhide(divID) {
var item = document.getElementById(divID);
if (item) {
item.style.display=(item.style.display=='block')?'none':'block';
}
}
</script>
PHP Code:
for($i=0; $i<$num_rows_publication; $i++)
{
echo ("<a href=\"javascript:unhide('content')\">" . mysql_result($result_publication, $i, "pubName") . "</a>");
$query_files = "SELECT * FROM files WHERE pubId = " .
mysql_result($result_publication, $i, "id") . " ORDER BY files.language";
$result_languages = mysql_query($query_files) or die(mysql_error());
$num_rows_languages = mysql_num_rows($result_languages);
for($j=0; $j<$num_rows_languages;$j++)
{
echo("<div id='content'>");
echo("<table>");
echo("<tr><td class='language'><a href='" . mysql_result($result_languages, $j, "file") . "'>" . mysql_result($result_languages, $j, "language") . "</a></td></tr>");
echo("</table>");
echo("</div>");
}
echo("<hr/>");
}