function show_content(self,id)
{
var parent = self.parentNode;
var childs = parent.getElementsByTagName('li');
var length= childs.length;
for(i=0;i<length;i++)
{
childs[i].className='hover_bg';
//alert(document.getElementById('c'+i).style.display)
document.getElementById('c'+i).style.display='none';
}
self.className='current_bg';
document.getElementById('c'+id).style.display='block';

}