sjbmaine on "CSS Styling Based on Grandparent Page? How to?"

I am using the following styling to pull in a custom banner for my pages. This works well for the top page and the child page. However, I've added a grandchild page. How would I modify the CSS to style the banner for the grandchild?

.page-id-9 #banner, .parent-pageid-9 #banner  {
	background: #15375e url('images/broadband.png') no-repeat left;