How to highlight child menu item, when I'm at the grandchild page?

Hi,

my site is still under construction, but I think, you can follow my question, when you look at the ENFOLD demo:

Let’s take this page:
http://kriesi.at/themes/enfold/shortcodes/animated-image/

• “Animated Image” is a child of “Shortcodes”
• When you are at the child page “Animated Image”, then in the main menu “Shortcodes” is highlighted

Now let’s suppose, that the child “Animated Image” has also a child (= grandchild of “Shortcodes”), let’s call this page “ABC”.

• “Animated Image” is a child of “Shortcodes”
• “ABC” is a child of “Animated Image”
• The main menu item “Shortcodes” is always highlighted: when you are at its child or at its grandchild page

So far, so fine.

BUT:

When I am at the grandchild page, then only the main menu item is “highlighted” (here: “Shortcodes” menu item), but not the child page “Animated Image”.

How do I write the CSS, so that the parent AND the child menu item is highlighted, when I am at the grandchild page?
I’ve made a quick composing, it should explain it better:

Thanks for your help.