"Highlight" a parent menu item when a child menu item is currently loaded?

I want a bottom border for the parent menu item displayed when the page of a sub-menu item is loaded. What CSS selector do I need to accomplish this? I have also tried adding parent instead of ancestor to the end of #access li.current-menu-item-ancestor > a and also tried parent and ancestor for #access li.current_page_item > a

Here is my CSS:

#access a:hover,
#access li.current_page_item > a,
#access li.current-menu-item > a ,
#access li.current-menu-item-ancestor > a{
	background:rgba(255, 255, 255, .2);
	color:#fff;
	text-decoration:none;
        border-bottom: 4px solid #D8D8D8;
}

Thanks in advance!