Sub menu - dropdown background - text colour - full width

Style / NAVBAR 

Dropdown background colour

Text colour

Sub menu drop down font size

 Now the active state colour needs to be set up like this:

In the item settings: Item > Settings > Item > Type > click on dynamic and select, Item

Item > Active click on dyanmic and select, Active - Menu item.

Full Width

Layout / Header / Dropdown / tick the radio button for Enable dropbar