I have a menu here...it relies on the <a> to change the background-position of the image and add a bottom-border to the surrounding <li> by adding a class. I need to add support for browsers that will not support the first-child/last-child pseudo classes...so I would like to add a style declaration (instead of a class change; <style.paddingLeft...> so that it adjusts the padding on the first and last node...with the Javascript so that I don't have to add actual classes to the <LI> items that will conflict with the existing script. I am having some problems and can't seem to find an example that is close enough to what I need done. Any help or links would be very much appreciated!! The current JavaScript is here:

Code:
<script type="text/javascript">
window.onload= function()
{
	var mylist= document.getElementById("headerNav");
    mylist.onmouseover= function(e)
	{
        e= window.event? event.srcElement: e.target;
        if(e.nodeName== 'A')
		{  
			var pa=e.parentNode;	
			pa.className= 'menuActive';					
		}
    }
	
    mylist.onmouseout= function(e)
	{
        e= window.event? event.srcElement: e.target;
        if(e.nodeName== 'A')
		{
    		var pa=e.parentNode;
    		pa.className= '';
    	}
	} 
}
</script>