function changeStyle(objId,styleName)
{
	document.getElementById(objId).className=styleName;
}



function changeClassOver(obj)
{
	if (obj == "for")
	{
		document.getElementById(obj).className="forwardbtn over";
	}
	if (obj == "bac")
	{
		document.getElementById(obj).className="backbtn overback";
	}
}

function changeClassUp(obj)
{
	if (obj == "for")
	{	
		document.getElementById(obj).className="forwardbtn";
	}
	if (obj == "bac")
	{		
		document.getElementById(obj).className="backbtn";
	}
}