Well,
the HREF tag is this:
<a href="javascript:chgSlide(-1)" onFocus="this.blur()"><?php echo $backbutton ?></a>
and this sets up the $backbutton variable:
if ($schemerow["backimage"] != "") {
$backbutton = "<img src=\"images/schemes/" . $scheme . "/" . $schemerow["backimage"] . "\" border=\"0\">";
} else {
$backbutton = "<font color=\"" . $directioncolor . "\" style=\"text-decoration: none\">" . $schemerow["backtext"] . "</font>";
}
The image outline I'm speaking of appears when an image button is clicked on, and if the button persists on the page (i.e. page doesn't reload) it tends to stay lit. A border, if not set to 0, is always visible, whether an image is clicked on or not.
I don't think this is just a Mac phenomenon - it's my understanding it happens on the Windows side too.