A basic navigation list is best used for navigating around the information within a single document. You can highlight the current section by adding the .active class to the list item wrapping the associated link.
Sub navigation
Navigation lists can be nested to show the hierarchy of information within a
document. simple place the sub navigation within a child list to apply the
desired styles. You will also need to add the .open class to the
parent list item inorder to highlight it correctly.