vertical header

I was wondering if someone could help me with OCEAN WP.

I have a vertical menu and I’m trying to configure it so the dropdown keeps open when i’m on a certain page, but only the dropdown for that page.

I have used this code:

#site-header.vertical-header #site-navigation-wrap .dropdown-menu > li.current-menu-parent .sub-menu { display: block !important; }

but the problem is that when it’s active all the dropdowns are open and the + symbol won’t work to close all the menu again. I want it to open the dropdown but only for the current page, what can I do?

The page I need help with: [log in to see the link]