Change colours of the navigation bar

[joicol]

I have a very simple question: how to change the colour of the navigation bar buttons to that of the theme colour ? Also I would like to change the mouse over colour of the buttons. I've added a screenshot. The arrow points to the (darkgreen) colour I would like the vertical/left navbar to look like.

I've tried everything from searching in the edit navbar settings to dragging and dropping one of the colours from the bottom bar. It's easy for the sub-menus, but not for the main navbar.