Navigational structures in responsive design
Navigation may appear differently on mobile and desktop devices. Desktops have much more horizontal space so the menu can be spread horizontally rather than collapsed under icons.
The need for the navigation to work on a mobile means a much shallower structure is required. It is important that users can access information quickly and easily without searching through layered navigation with many subcategories like on desktop websites.
Your navigation also needs to be succinct and informed by the user journeys identified in the research phase of the project.